[lldb] Use LLVM's implementation of AppleTables for apple_{names,namespaces}

All the new code should match the behavior of the old exactly.

Of note, the custom queries used to be implemented inside `HashedNameToDIE.cpp`
(which is the LLDB implementation of the tables). However, when porting to LLVM,
we believe they don't belong inside the LLVM table implementation:

1. They don't require any knowledge about the table itself
2. They are not relevant for other users of these classes.
3. They use LLDB data structures.

As such, we implement these custom queries inside AppleDWARFIndex.cpp.

Types and Objective-C tables are done separately, as they have slightly
different functionality that require rewriting more code.

Differential Revision: https://reviews.llvm.org/D153866