Remove Bloop server modules

[alexarchambault]

This is an attempt to remove the server-related modules (shared, backend, frontend) from this repository, using the ones from the Scala CLI fork instead. This leaves behind… whatever remains (soon-to-be-deprecated launcher stuff, possibly soon-to-be-deprecated bloopgun stuff, docs, sbt-bloop, buildpress, …)

Checking how the CI goes for now.

[alexarchambault]

The error originates from the frontend module in scala-cli/bloop-core not pushing a test JAR to Maven Central.

[tgodzik]

I went the other way to include the bloop fork inside the original Bloop