Incompatibility with various Android keyboards; wrap vosk-android in IME service (especially for standalone use/accessibility)

As of 5e02806*, the vosk service is fully functional/compatible with AnySoftKeyboard, but incompatible with OpenBoard and FlorisBoard**. Both of the latter use the inputmethodmanager framework as opposed to interacting with the speechrecognition service, and do not identify the vosk service as an input method.

Given that there is no open-source stt alternative to Google, etc. at time of posting (3/2023), relying on the SpeechRecognitionService is appropriate***. The vosk service works totally fine as a (de-facto) plugin for AnySoft. However, switching to/stuffing an IME service on top of vosk-android as a standalone service would be nice for accessibility (i.e. for those with disabilities due to which it would make sense to use voice as *the* IME). This isn't unreasonable given that Google already does this with speech services.

Without significant experience with IMM/IMEs, I think that this should be pretty straightforward: add an intermediate level activity on top of the vosk-recognition-service that can be forked off in the manifest as its own service. Then, the given keyboard can decide which service to latch onto for STT.

*additional configuration:
Build Configuration: Gradle Toolkit command-line, debug w/universal apk (compilesdk 33)
Gradle toolkit version: 7.6 (defaults despite the build kts depending on 7.2.2; no api level spec'd); builds against OpenJDK-14
Device: Pixel 3
Device OS: Android 12
Additional Device Apps: AnySoftKeyboard (v1.11.7137/F-droid; UTD)

**nothing special per se about these two keyboards. I chose them as the major open alternatives I've seen on reddit and f-droid. Of note, I haven't tested konele, but would be surprised if it wasn't compatible given @ccoreilly's efforts with localstt.

***I am hesitant to say that choosing that IMM/IME is better vs direct-speech recognition service, or on any ime designer's preference to use either. Per above, I don't think that either are incompatible per se, and can be construed to have separate use cases. **Any thoughts would be appreciated.** Tagging some people who may have some useful input: @patrickgold, @dslul, @ewheelerinc, @ildar, @kaljurand, @felicis. CC:@stypox

Edit: misspelled kaljurand, added stypox.