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>

ReadMe.md

@@ -29,11 +29,11 @@ They both must be flashed in the order described.
 
 With Flipper attached over USB:
 
-`./fbt --with-updater flash_usb`
+`./fbt flash_usb`
 
 Just building the package:
 
-`./fbt --with-updater updater_package`
+`./fbt updater_package`
 
 To update, copy the resulting directory to Flipper's SD card and navigate to `update.fuf` file in Archive app.