compile dotty with Ysemanticdb

[bishabosha]

fix #8970 fix #8954

fix a number of issues with semanticdb generation

• support scala 2 def macros
• support var overloads
• support literal types and byname params in constructors (by removing unneccesary code)
• support local definitions from inlined macro generated trees (where symbol has no span)
• prevent infinite recursion on traversal of annotations
• support inlined macro trees from another file
• do not emit occurence for <special-ops>.throw
• inlined trees have position in the file of the callsite, not implementation

this also compiles all of the vulpix tests with Ysemanticdb option and the bootstrapped projects (localised to 1 commit)

[bishabosha]

this will fail until I rebase it on a PR to always provide spans if possible for symbols from TASTy

Now implemented change to provide spans from tasty when semanticdb is set

[bishabosha]

@smarter I've added a change here so that compiler newRun enables ReadPositions if Ysemanticdb setting is true