[DWARFLinker][DWARFv5] Add handling of DW_OP_addrx and DW_OP_constx expression operands.

This patch adds handling of DW_OP_addrx and DW_OP_constx expression operands.
In --update case these operands are preserved as is. Otherwise they are
converted into the DW_OP_addr and DW_OP_const[*]u correspondingly.

Differential Revision: https://reviews.llvm.org/D147066