Add auto-formatting to build pipeline

[david-allison]

• rustfmt
• Some Java formatting (Google?)

[mikehardy]

This is interesting - some other repos I work on have cast about for something for java

https://github.com/google/google-java-format

And their release notes may incidentally fix the AnkiDroid JDK16 build issue ankidroid/Anki-Android#8434 !

https://github.com/google/google-java-format#jdk-16

[mikehardy]

this is in actual use in a repo I maintain with others, and thus maybe useful as a recipe

"format:android": "google-java-format --replace -i $(find . -type f -name "*.java")",

[dae]

Rust formatting is already covered by CI / check-rust.sh. Kotlin formatting could presumably be handled in a similar way Anki-Android.