Show github actions build number in startup log and version check command

[onebeastchris]

Changes made:

• Version checker shows build number (https://mclo.gs/MTMmJ4B)
• Added dev build warning in both startup and version check command - depends on https://github.com/GeyserMC/languages/pull/118
• Updated version checking command - thanks @Jens-Co for that, was allowed to take that from his old PR.

TODO's:

• yeet md5 hash from dump? - the downloads api does not provide it

Would fix https://github.com/GeyserMC/Geyser/issues/1748

[Kas-tle]

Must be adapted as build number is no longer pulled directly from GH actions and instead uses the env variable BUILD_NUMBER. See https://github.com/GeyserMC/Geyser/pull/4583/files#diff-a6fced4b4e4a99784a2b92028b1adbc8c0ca28ff54e264b0e73727b3d4a460cf.