fbt fixes & improvements (#1490)

* fbt: minimal USB flash mode; scripts: faster storage.py with larger chunks
* fbt: fixed creation of temporary file nodes confusing scons
* docs: removed refs to --with-updater
* fbt: removed splashscreen from minimal update package
* fbt: renamed dist arguments for consistency
* docs: fixed updater_debug target
* fbt: separate target for generating compilation_database.json without building the code.
* fbt: added `jflash` target for programming over JLink probe; refactored usb flashing targets
* fbt: building updater_app in unit_tests configuration
* fbt: fixed reset behavior after flashing with J-Link
* fbt: generating .map file for firmware binary & external apps
* fbt/core: moved library contents before apps code

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

fbt_options.py

@@ -80,6 +80,7 @@ FIRMWARE_APPS = {
     ],
     "unit_tests": [
         "basic_services",
+        "updater_app",
         "unit_tests",
     ],
 }