Optimize BSP compilation for Scala 3

[lefou]

Currently the BSP compilation for Scala Modules combines the results of the compile and the semanticDbData tasks. This assumes, that semanticDbData is produced in addition to the compilation. Effectively, in Scala 3 we can't produce semanticDb data without completely compiling the code (using -Ystop-after: doesn't work as it did in Scala 2). Hence, the result of compile is redundant to the result of semanticDbData. In BSP, we should avoid the compile evaluation all together, to reduce work.