[Refactoring] fix indent style
[Refactoring] A little code cleanup in _aaGetX, _aaGetRvalueX, and _aaInX
[Refactoring] Remove code duplication
Merge pull request #1024 from 9rnsr/refactor_aa

[Refactoring] Remove code duplication in rt/aaA.d
fix for issue 13701, improve AA.dup for const values