[clang][analyzer] Support `ownership_{returns,takes}` attributes (#98941)

Add support for checking mismatched ownership_returns/ownership_takes attributes.

Closes #76861

[analyzer] Handle builtin functions in MallocChecker (#88416)

This commit ensures that the `CallDescription`s in `MallocChecker` are
matched with the mode `CDM::CLibrary`, so:
- they don't match m

[analyzer] Handle builtin functions in MallocChecker (#88416)

This commit ensures that the `CallDescription`s in `MallocChecker` are
matched with the mode `CDM::CLibrary`, so:
- they don't match methods or functions within user-defined namespaces;
- they also match builtin variants of these functions (if any), so the
checker can model `__builtin_alloca()` like `alloca()`.

This change fixes https://github.com/llvm/llvm-project/issues/81597. New
tests were added to verify that `std::malloc` and `std::free` (from
`<cstdlib>`) are modeled, but a method that's named e.g. `free` isn't
confused with the memory release function.

The responsibility for modeling `__builtin_alloca` and
`__builtin_alloca_with_align` was moved from `BuiltinFunctionChecker` to
`MallocChecker`, to avoid buggy interactions between the checkers and
ensure that the builtin and non-builtin variants are handled by exactly
the same logic.

This change might be a step backwards for the users who don't have
`unix.Malloc` enabled; but I suspect that `__builtin_alloca()` is so
rare that it would be a waste of time to implement backwards
compatibility for them.

There were several test files that relied on `__builtin_alloca()` calls
to get an `AllocaRegion`, these were modified to enable `unix.Malloc`.
One of these files (cxx-uninitialized-object-ptr-ref.cpp) had some tests
that relied on the fact that `malloc()` was treated as a "black box" in
them, these were updated to use `calloc()` (to get initialized memory)
and `free()` (to avoid memory leak reports).

While I was developing this change, I found a very suspicious assert in
`MallocChecker`. As it isn't blocking the goals of this commit, I just
marked it with a FIXME, but I'll try to investigate and fix it in a
follow-up change.

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