Add JNI bindings along with a package

[jerinphilip]

Add JNI bindings for use via Java (intended for an offline translation android application). The cache which is meant to speed up translations (especially while typing), which was not working previously is configured to work now.

MacOS CI requires some fixing since SentencePiece 0.2.0 (via brew) breaks some assumptions here. Using internal sentencepiece for time-being as a stopgap solution.

---

Attempting to use the models in an android-application. Hypothesis is it is simpler to export a .jar file from here following native-library requirements (preferably from the current android build).

Maybe I can use cmake voodoo to build this jar and ship as an artifact?

Once built for a armv8a ABI, should be portable across a lot of devices (at least my device).

• https://stackoverflow.com/questions/2937406/how-to-bundle-a-native-library-and-a-jni-library-inside-a-jar
• https://chat.openai.com/share/6e755360-d185-454c-a844-1261d1fa4d67

I really only care about android-armv8a at the moment, wider JNI can be applied if and when required.

Works. Tecno Pova 3 (LF7)

Don't know java, so let's compile some guides:

1. https://stackoverflow.com/questions/8135282/entity-class-string-vs-liststring
2. https://stackoverflow.com/questions/3226282/are-there-best-practices-for-java-package-organization