[FL-3211][FL-3212] Debug apps: speaker, uart_echo with baudrate (#2812)

* Music player: move music_worker to library
* Music player: drop cli
* Debug: speaker debug app
* Debug: baudrate arg in uart_echo app
* Libs: add music_worker to api
* Libs: add music_worker to targets linker_dependencies

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

lib/music_worker/SConscript

@@ -0,0 +1,27 @@
+Import("env")
+
+env.Append(
+    CPPPATH=[
+        "#/lib/music_worker",
+    ],
+    SDK_HEADERS=[
+        File("music_worker.h"),
+    ],
+)
+
+libenv = env.Clone(FW_LIB_NAME="music_worker")
+libenv.ApplyLibFlags()
+
+libenv.AppendUnique(
+    CCFLAGS=[
+        # Required for lib to be linkable with .faps
+        "-mword-relocations",
+        "-mlong-calls",
+    ],
+)
+
+sources = libenv.GlobRecursive("*.c*")
+
+lib = libenv.StaticLibrary("${FW_LIB_NAME}", sources)
+libenv.Install("${LIB_DIST_DIR}", lib)
+Return("lib")