fbt: fixes for ufbt compat (#1940)

* fbt: split sdk management code
* scripts: fixed import handling
* fbt: sdk: reformatted paths
* scrips: dist: bundling libs as a build artifact
* fbt: sdk: better path management
* typo fix
* fbt: sdk: minor path handling fixes
* toolchain: fixed windows toolchain download

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

scripts/fbt_tools/fbt_extapps.py

@@ -8,7 +8,7 @@ import os
 import pathlib
 from fbt.elfmanifest import assemble_manifest_data
 from fbt.appmanifest import FlipperApplication, FlipperManifestException
-from fbt.sdk import SdkCache
+from fbt.sdk.cache import SdkCache
 import itertools
 from ansi.color import fg