[FL-870] Auto-generated firmware documentation take two (#2944)

* Add doxygen and doxygen-awesome css, cleanup docs files
* Ignore more libraries and remove leftover local variables
* Create an actual intro page
* .md files linting
* Add doxygen action
* Fix Doxygen path
* Fix doxyfile path
* Try to upload
* Change docs branch
* Add submudules checkout
* Disable doxygen on PR
* Mention the firmware docs in the readme
* More dev docs mentions in the readme
* Fix runner group, add tags
* Test dev in PR
* Disable running on PR
* Fix a typo in the doxyfile
* Try upload to S3
* Fix local path
* Fix S3 ACL
* Add delete flag, unifying dev and tags
* Update ignored directories
* More ignored directories
* Even more ignored directories
* Fix submodule
* Change S3 uploader
* Change S3 uploader version
* Fix aws sync flags
* Fix ACL
* Disable ACL
* Improve ignores, add WiFi devboard docs
* TEMP: generate dev docs
* TEMP: generate 0.89.0 docs
* Disabling PR trigger
* Enable submodules and test build
* Enable test build
* Disable test build
* Change docs directory structure
* Fix accidentally committed submodule
* Fix submodules
* Update links to the developer documentation
* Markdown linting
* Update workflow, enable test build
* Fix doxygen dir path
* Update Doxyfile-awesome.cfg
* Change paths
* Fix upload docs path
* Disable pull_request debug trigger
* Disable tags building
* Remove autolinks and namespaces
* Establish basic documentation structure
* Add missing changes
* Improve stylesheet, move some files
* Improve examples
* Improve the main page
* Improve application dev docs
* Improve system programming docs
* Improve development tools docs
* Improve other docs
* Improve application examples
* Fix formatting
* Fix PVS-studio warnings
* Improve visuals
* Fix doxygen syntax warnings
* Fix broken links
* Update doxygen action

Co-authored-by: DrunkBatya <drunkbatya.js@gmail.com>
Co-authored-by: あく <alleteam@gmail.com>
Co-authored-by: Georgii Surkov <georgii.surkov@outlook.com>
Co-authored-by: Georgii Surkov <37121527+gsurkov@users.noreply.github.com>

documentation/UnitTests.md

@@ -1,11 +1,11 @@
-# Unit tests
+# Unit tests {#unit_tests}
 
 ## Intro
 
 Unit tests are special pieces of code that apply known inputs to the feature code and check the results to see if they are correct.
 They are crucial for writing robust, bug-free code.
 
-Flipper Zero firmware includes a separate application called [unit_tests](/applications/debug/unit_tests).
+Flipper Zero firmware includes a separate application called [unit_tests](https://github.com/flipperdevices/flipperzero-firmware/tree/dev/applications/debug/unit_tests).
 It is run directly on Flipper devices in order to employ their hardware features and rule out any platform-related differences.
 
 When contributing code to the Flipper Zero firmware, it is highly desirable to supply unit tests along with the proposed features.
@@ -20,7 +20,7 @@ To run the unit tests, follow these steps:
 3. Launch the CLI session and run the `unit_tests` command.
 
 **NOTE:** To run a particular test (and skip all others), specify its name as the command argument.
-See [test_index.c](/applications/debug/unit_tests/test_index.c) for the complete list of test names.
+See [test_index.c](https://github.com/flipperdevices/flipperzero-firmware/blob/dev/applications/debug/unit_tests/test_index.c) for the complete list of test names.
 
 ## Adding unit tests
 
@@ -28,11 +28,11 @@ See [test_index.c](/applications/debug/unit_tests/test_index.c) for the complete
 
 #### Entry point
 
-The common entry point for all tests is the [unit_tests](/applications/debug/unit_tests) application. Test-specific code is placed into an arbitrarily named subdirectory and is then called from the [test_index.c](/applications/debug/unit_tests/test_index.c) source file.
+The common entry point for all tests is the [unit_tests](https://github.com/flipperdevices/flipperzero-firmware/tree/dev/applications/debug/unit_tests) application. Test-specific code is placed into an arbitrarily named subdirectory and is then called from the [test_index.c](https://github.com/flipperdevices/flipperzero-firmware/tree/dev/applications/debug/unit_tests/test_index.c) source file.
 
 #### Test assets
 
-Some unit tests require external data in order to function. These files (commonly called assets) reside in the [unit_tests](/applications/debug/unit_tests/resources/unit_tests) directory in their respective subdirectories. Asset files can be of any type (plain text, FlipperFormat (FFF), binary, etc.).
+Some unit tests require external data in order to function. These files (commonly called assets) reside in the [unit_tests](https://github.com/flipperdevices/flipperzero-firmware/tree/dev/applications/debug/unit_tests/resources/unit_tests) directory in their respective subdirectories. Asset files can be of any type (plain text, FlipperFormat (FFF), binary, etc.).
 
 ### Application-specific
 
@@ -41,9 +41,9 @@ Some unit tests require external data in order to function. These files (commonl
 Each infrared protocol has a corresponding set of unit tests, so it makes sense to implement one when adding support for a new protocol.
 To add unit tests for your protocol, follow these steps:
 
-1. Create a file named `test_<your_protocol_name>.irtest` in the [assets](/applications/debug/unit_tests/resources/unit_tests/infrared) directory.
+1. Create a file named `test_<your_protocol_name>.irtest` in the [assets](https://github.com/flipperdevices/flipperzero-firmware/tree/dev/applications/debug/unit_tests/resources/unit_tests/infrared) directory.
 2. Fill it with the test data (more on it below).
-3. Add the test code to [infrared_test.c](/applications/debug/unit_tests/infrared/infrared_test.c).
+3. Add the test code to [infrared_test.c](https://github.com/flipperdevices/flipperzero-firmware/blob/dev/applications/debug/unit_tests/infrared/infrared_test.c).
 4. Build and install firmware with resources, install it on your Flipper and run the tests to see if they pass.
 
 ##### Test data format