Have more information in DuplicateSelectiveImport

[flip111]

The DuplicateSelectiveImport warning currently only records the name of the module that is duplicated. Could it additionally record in the data structures:

• line numbers of duplicates :: List Integer
• "It could be replace with: ..." :: Text

This way refactoring tools can just remove the lines and replace it with the suggested line. Otherwise the tool has to parse the purescript source code again when it has been already parsed.

I don't mind either way if the textual message to the user changes or not. But having these additions to the JSON would be great. So either as part of the message or as separate fields in the JSON.