[DWARF5] Added support for .debug_macro.dwo section in llvm-dwarfdump

This patch extends the parsing and dumping support of llvm-dwarfdump
for debug_macro.dwo section.

Following forms are supported:

 - DW_MACRO_define
 - DW_MACRO_undef
 - DW_MACRO_start_file
 - DW_MACRO_end_file
 - DW_MACRO_define_strx
 - DW_MACRO_undef_strx
 - DW_MACRO_define_strp
 - DW_MACRO_undef_strp

Reviewed by: ikudrin, dblaikie

Differential Revision: https://reviews.llvm.org/D78500