[ObjectYAML][ELF] Add support for emitting the .debug_line section.

This patch enables yaml2elf emit the .debug_line section.

Test cases for emitting the dwarf64 .debug_line section and opcodes will be added later.

Known issues:
- We should replace `InitialLength` with `Format` and `Length`
- Currently implementation of the .debug_line section only fully supports DWARFv2, some header fields in DWARFv4 and DWARFv5 is missing, e.g., `header_length` in DWARFv4, `address_size` and `segment_selector_size` in DWARFv5.
- Some opcodes relies on the .debug_info section, we should warn user about it.

These issues will be addressed in a follow-up patch.

Reviewed By: jhenderson, grimar

Differential Revision: https://reviews.llvm.org/D81450