[FL-3627, FL-3628, FL-3631] fbt: glob & git improvements (#3151)

* fbt: optional shallow submodule checkout
* fbt: more git threads by default
* fbt: git condition fix
* fbt: renamed FBT_SHALLOW to FBT_GIT_SUBMODULE_SHALLOW
* github: enabled   FBT_GIT_SUBMODULE_SHALLOW in flows
* fbt: always compile icons' .c, even if user does not specify a proper source glob; changed glob to require files at user-specified paths to exist
* fbt: fail build for missing imports in .faps
* fbt: moved STRICT_FAP_IMPORT_CHECK to commandline options; enabled by default
* ufbt: enabled STRICT_FAP_IMPORT_CHECK

Co-authored-by: あく <alleteam@gmail.com>

.github/workflows/build.yml

@@ -11,6 +11,7 @@ on:
 env:
   DEFAULT_TARGET: f7
   FBT_TOOLCHAIN_PATH: /runner/_work
+  FBT_GIT_SUBMODULE_SHALLOW: 1
 
 jobs:
   main:

.github/workflows/build_compact.yml

@@ -5,6 +5,7 @@ on:
 
 env:
   FBT_TOOLCHAIN_PATH: /runner/_work
+  FBT_GIT_SUBMODULE_SHALLOW: 1
 
 jobs:
   compact:

.github/workflows/pvs_studio.yml

@@ -10,6 +10,7 @@ env:
   TARGETS: f7
   DEFAULT_TARGET: f7
   FBT_TOOLCHAIN_PATH: /runner/_work
+  FBT_GIT_SUBMODULE_SHALLOW: 1
 
 jobs:
   analyse_c_cpp:

.github/workflows/unit_tests.yml

@@ -7,6 +7,7 @@ env:
   TARGETS: f7
   DEFAULT_TARGET: f7
   FBT_TOOLCHAIN_PATH: /opt
+  FBT_GIT_SUBMODULE_SHALLOW: 1
 
 jobs:
   run_units_on_bench:

.github/workflows/updater_test.yml

@@ -7,6 +7,7 @@ env:
   TARGETS: f7
   DEFAULT_TARGET: f7
   FBT_TOOLCHAIN_PATH: /opt
+  FBT_GIT_SUBMODULE_SHALLOW: 1
 
 jobs:
   test_updater_on_bench: