[DebugInfo] Support for DWARF attribute DW_AT_rank

This patch adds support for DWARF attribute DW_AT_rank.

  Summary:
Fortran assumed rank arrays have dynamic rank. DWARF attribute
DW_AT_rank is needed to support that.

  Testing:
unit test cases added (hand-written)
check llvm
check debug-info

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D89141