[DebugInfo] Change return type of DWARFDebugAbbrev::parse (#67191)

To make DWARFDebugAbbrev more amenable to error-handling, I would like
to change the return type of DWARFDebugAbbrev::parse from `void` to
`Error`. Users of DWARFDebugAbbrev can consume the error if they want to
use all the valid DWARF that was parsed (without worrying about the
malformed DWARF) or stop when the parse fails if the use case needs to
be strict.

This also will bring the LLVM DWARFDebugAbbrev interface closer to
LLDB's which opens up the opportunity for LLDB adopt the LLVM
implementation with minimal changes.