[clang] [clang][analyzer] Add OpaqueSTLFunctionsModeling (PR #178910)

[Balázs Benics via cfe-commits]

steakhal wrote:

It turns out that with the `%clang_analyze_cc1` we bypass the usual clang driver, thus the flags that translates to the cc1 driver of the analyzer will not be invoked. That means that the default checkers are not enabled, and that's why we need to explicitly set `core` and friends. Otherwise only the syntax based checkers would run - completely skipping the path-sensitive analysis part.
Consequently, I had to revert explicitly enabling that core and apiModeling packages.
As I was there already, I just use `count` instead of `FileCheck` to simplify the test.

https://github.com/llvm/llvm-project/pull/178910