## App state
Improved app state management in `LoaderService` and `GuiService`:
- Re-ordered some of the state transitions
- Hardened `GuiService` for repeated events (that might trigger a re-render of an app that's already rendered)
- Validate state transitions in `LoaderService` and crash if an app transitions from the wrong state to the next one.
## LoaderService
- Removed `tt::loader::` functions and expose `LoaderService` interface publicly.
- Implement `stopAll()` and `stopAll(id)` which stops all instances of an app, including any apps that were launched by it.
- Rename `stop()` functions to `stopTop()`
- Created `stopTop(id)` which only stops the top-most app when the app id matches.
- Moved `loader::LoaderEvent` to `loader::LoaderService::Event`
- Changed app instance `std::stack` to `std::vector`
## Improvements
- `ElfApp`: error 22 now shows a hint that `main()` might be missing
- Starting, installing and uninstalling apps now stops any running app (and its children) on the stack
## Bugfixes
- `HttpdReq` out of memory issue now shows an error message and doesn't crash anymore (this would happen on devices without PSRAM with WiFi active, when an app was installed)
- `GuiService::hideApp()` lock should not wait for timeout and now waits indefinitely
- `Buildscript/release-sdk-current.sh` deletes the previous local release before building a new one
## Code correctness
- App classes were made `final`
- Apps that had a `void start()` now have a `LaunchId start()`
- `tt::app::State`: renamed `Started` to `Created` and `Stopped` to `Destroyed` to properly reflect earlier name changes
- GitHub actions changed to build simulator on macOS (it's broken, but at least we get a good code portability check for now!)
- `Buildscripts/` shell scripts updated to use `/bin/sh` so it works on macOS too
- Various includes fixed in various subprojects so the code is more portable
