[clang] [clang-tools-extra] [Clang] [NFC] Migrate more AST visitors (PR #160290)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

This all seems really mechanical as well, so I dont' have any concerns with that. However, the compile-time-tracker _IS_ a bit concerning.  The DRAV vs RAV decision is very much a performance-vs-size debate, and I don't like that we're giving up a percent+ on a few of these benchmarks (between this and the last one) in exchange for this size.

What I would LIKE to see is some analysis of:
1- How many instantiations these have
    -Thus: How much space taken, and saved by switch
2- Which are hot-path enough to affect benchmarks, and which are irrelevant

For example, the tooling, unittests, tidy/etc variants seem like an easy decision for me, even if the answer to 1 above is "only 1 instantiation".

However, the ones in CodeGen or AST, or Debug info, etc, I'd want to see a significant savings, since those clearly affect compile time.

https://github.com/llvm/llvm-project/pull/160290