Add IDExxx rule for converting multiline string to raw string

Currently there is only “Convert to raw string” code refactoring with fix-all support (weird. How can a refactoring has fix all? I doesn’t fix anything). Using this fix-all is not much helpful as it converts all strings to raw form, even simple single-line onse, e.g. "a" -> """a""". It would be a lot more helpful if there is an IDExxx rule for converting only multiline strings to raw form, .e.g

@"First line
Second line
"

to

"""
First line
Second line
"""

Such rule should check for language version and probably be suggestion by default.

[DoctorKrolic]

lots of refactorings could be converted to analyzer/codefix

I don’t suggest to convert this refactoring to codefix entirely. My proposal is to leave refactoring for singleline strings (probably without fix all as it would probably have very limited scope of usages) and make IDExxx rule only for multiline cases

[CyrusNajmabadi]

Refactoring doesn’t fix anything, so it cannot have fix all scopes)

Sure it can. It’s the scopes that the code fixup is applied to. ‘fix’ doesn’t mean “broken”. It’s akin to “fixing lunch” 😃