In an effort to unify the different dwarf parsers available in the codebase,
this commit removes LLDB's custom parsing for the `.debug_ranges` DWARF section,
instead calling into LLVM's parser.
Subsequent work should look into unifying `llvm::DWARDebugRangeList` (whose
entries are pairs of (start, end) addresses) with `lldb::DWARFRangeList` (whose
entries are pairs of (start, length)). The lists themselves are also different
data structures, but functionally equivalent.
Depends on D150363
Differential Revision: https://reviews.llvm.org/D150366