[clang] [analyzer][NFC] Merge `BlockInvocationContext` class into `StackFrameContext` (PR #194857)

[Balázs Benics via cfe-commits]

steakhal wrote:

> `<offtopic>`
> 
> > > (By the way, for some reason this separation was not applied among the tests, so the static analyzer tests remained under `test/Analysis` and eventually "crowded out" all the other tests. I moved the last non-analyzer tests from `test/Analysis` to other directories ~ a year ago.)
> > 
> > 
> > I think a split of `test/Analysis` is slowly brewing. It's not urgent or a blocker though.
> 
> There is nothing to **split** in the directory `test/Analysis`: currently it _only_ contains tests for the static analyzer (and perhaps analyzer-dependent utilities like the exploded graph rewriter). The tests of the `lib/Analysis` area are scattered elsewhere (IIRC in `test/Sema` and similar directories).
> 
> However, it would be reasonable to **rename** `test/Analysis` to `test/StaticAnalyzer` to avoid confusion.
> 
> @steakhal WDYT? `</offtopic>`

Probably yes, but we need to look at the RUN lines to confirm that no clang-frontend diags sneaked in, for example for anything implemented by clang/lib/Sema/AnalysisBasedWarnings.cpp.

Also note that `Scalable` subdirectories would need to be moved out then - for the better.

https://github.com/llvm/llvm-project/pull/194857