[Refactoring] Improve `Type::addSTC`
[Refactoring] Improve `Parser::parseType` by using `Type::addSTC`
[Refactoring] Improve CastExp parsing by using `Type::addSTC`
fix Issue 11768 - inconsistent behavior of type qualifier inout + const

Fix up `Parser::parseBasicType` by using `Type::addSTC`
[style] fix indent
Clean up inout deduction

- Rename `Type::wildConvTo` to `deduceWild`
- Use `wildmatch` for sum of arguments match level, and use `wm` for one parameter match level.
- Extract current workarounds for issue 6930
fix Issue 6930 - combined type of immutable(T) and inout(T) should be inout(const(T))