Previously we only generated declaration fragments for template type
parameters/arguments, this adds supports for most other possible
template parameters/arguments.

rdar://127732598

Reenables b31414bf4f9898f7817a9fcf8a91f62ec26f3eaf.

Also adds a new warning for missing `--symbol-graph-dir` arg when
`--emit-extension-symbol-graphs` is provided. This also reverts the
commit that removed.

This failed the test suite due to missing DiagGroup for a new warning.

This reverts commit b31414bf4f9898f7817a9fcf8a91f62ec26f3eaf.

This extends ExtractAPI to take into account symbols defined in categories to types defined in an external module.
This introduces 2 new command line flags, `--symbol-graph-dir=DIR` and `--emit-extension-symbol-graphs`, when used together this generates additional symbol graph files at `DIR/ExtendedModule@ProductName.symbols.json` for each external module that is extended in this way.

Additionally this makes some cleanups to tests to make them more resilient and cleans up the `APISet` data structure.

Other implementations of the symbol graph format use zero-based indices
for source locations, which causes problems when combined with clang's
current one-based indices. This commit sets ExtractAPI's symbol graph
output to use zero-based indices to align with other implementations.

rdar://107639783

Add has_template template, DeclarationFragmentBuilder functions, and tests for class templates, specializations/partial specs, and concepts.

Depends on D157007

Reviewed By: dang

Differential Revision: https://reviews.llvm.org/D157076