Move Type::toArgTypes into a visitor class
fix Issue 12097 - Ddoc unittest should generate consistent result with 'ditto' declarations
Merge pull request #3230 from 9rnsr/fix12097

Issue 12097 - Ddoc unittest should generate consistent result with 'ditto' declarations
Merge pull request #3226 from yebblies/toargtypes

[DDMD] [refactor] Move Type::toArgTypes into a visitor class
Remove Expression::useValue and all uses