[FL-3600] Added fal_embedded parameter for PLUGIN apps (#3083)

* fbt, ufbt: added `fal_embedded` parameter for PLIGIN apps, to embed them into .fap
* fbt: fixed dependency settings for assets
* fbt: extapps: Removed unneeded casts
* fbt: extapps: code simplification
* fbt: fal_embedded: fixed dependency relations

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

documentation/AppManifests.md

@@ -56,6 +56,7 @@ The following parameters are used only for [FAPs](./AppsOnSDCard.md):
 - **fap_weburl**: string, may be empty. Application's homepage.
 - **fap_icon_assets**: string. If present, it defines a folder name to be used for gathering image assets for this application. These images will be preprocessed and built alongside the application. See [FAP assets](./AppsOnSDCard.md#fap-assets) for details.
 - **fap_extbuild**: provides support for parts of application sources to be built by external tools. Contains a list of `ExtFile(path="file name", command="shell command")` definitions. **`fbt`** will run the specified command for each file in the list.
+- **fal_embedded**: boolean, default `False`. Applies only to PLUGIN type. If `True`, the plugin will be embedded into host application's .fap file as a resource and extracted to `apps_assets/APPID` folder on its start. This allows plugins to be distributed as a part of the host application.
 
 Note that commands are executed at the firmware root folder, and all intermediate files must be placed in an application's temporary build folder. For that, you can use pattern expansion by **`fbt`**: `${FAP_WORK_DIR}` will be replaced with the path to the application's temporary build folder, and `${FAP_SRC_DIR}` will be replaced with the path to the application's source folder. You can also use other variables defined internally by **`fbt`**.