Add Biome assists support

I want to have biome run assists as well, particularly [organize-imports](https://biomejs.dev/assist/actions/organize-imports/).
This would require to run the `check` command, instead of `format`.

Various other formatters (java, kotlin...) support organizing imports via Spotless, so it should be quite natural to have Biome provide similar capabilities.

As discussed in #2275 linting is however not the focus of Spotless, hence should be disabled.