Add -1 for any diagnostics using point() in Scala 3

[tgodzik]

This came up in case of ambigous implicits:

-- Error: dotty-interpolation.scala:23:15 --------------------------------------
23 |    val xx = fn    
   |               ^
   |ambiguous implicit arguments: both object c1 in class App and object c2 in class App match type App.this.C of parameter c of method fn in class App

diagnostic seems to be pointing to the place the parameters are supposed to be, which is not a real position. We need to do -1 in those cases, though not 100% sure it will work in every situation, but we can fix it as we find more issues.

[kpbochenek]

just minor comments not even directly related to your changes, ignore if you want :)

fix LGTM 👍

[kpbochenek]

pos: SourcePosition <- will never be optional

[kpbochenek]

(comment not related to this line but parameter of this method)

[tgodzik]

I have not noticed! Thanks and fixed!

[kpbochenek]

val position = pos.get <- never used (not related to this exact line)

[tgodzik]

Right! Fixed together with the previous one.

[kpbochenek]

rename test, one above is called the same

[tgodzik]

Fixed!

[tgodzik]

I will go ahead and merge. Might not be the best possible solution, but it fixes it for now and might not be an issue in the long run. I think point will mostly be needed to be used in cases when diagnostic is reported after a symbol. Alternative approach would be to modify edit distance to try to catch previous token if the one at the current position does not exist, but that would also change the bahaviour for Scala 2, which I don't want to currently do as the Scala 3 approach might still evolve.