[PoC] Extract convert import wildcard to start as independent rewrite

[kaatzee]

I would like to know if such change has a chance to be added.
The scenario in which such functionality is needed is when I want to rewrite underscores in imports to stars, but leave possibility to use both old and new syntax for if control syntax.
Currently when I set:

• rewrite.scala3.convertToNewSyntax = true and allowStarWildcardImport = true and allowSignificantIndentation = true all old if syntax is rewritten to new one
• rewrite.scala3.convertToNewSyntax = true and allowStarWildcardImport = true and allowSignificantIndentation = false it fails on places where new syntax of if is used.

Let me know what do you think and what further changes are needed to add this functionality.

[kitbellew]

@kaatzee what's the reason for this requirement? are import underscores deprecated whereas "old" if syntax is not?

[kaatzee]

@kitbellew yes, exactly. I have seen your PR which addresses this approach. Thank you! I am closing this PR then.