[clang] [clang][NFC] Refactor expected directives in C++ DRs 1-99 (PR #73879)

[Erich Keane via cfe-commits]

erichkeane wrote:

> > I could nit on the naming conventions here or there, but I think this overall is such a vast improvement that I'd rather get 'this', then argue on names in future files, and let this one lie.
> 
> @erichkeane Now is the best time to bring those nits on, unless you want changes in C++ code (this is out of scope of this PR and my current efforts, which is focused on `expected` directives). I've been striking balance with both `-verify` prefixes naming and `#marker` names, so I'm very open to input on those names.

I am ok with the bookmark names, but the 'verify' names seem really confusing.  I don't really have a better suggestion unfortunately, so my response would be mostly grumbling that they're not all the same format.  Perhaps a 'standardized' 'set' that we use everywhere would be less confusing.

https://github.com/llvm/llvm-project/pull/73879