…eland)' to release/18.x

(cherry picked from commit ee01a2c)

This re-applies 30155fc with a fix for clangd.

clang don't evaluate the object argument of `static operator()` and
`static operator[]` currently, for example:

```cpp

struct Foo {
    static int operator()(int x, int y) {
        std::cout << "Foo::operator()" << std::endl;
        return x + y;
    }
    static int operator[](int x, int y) {
        std::cout << "Foo::operator[]" << std::endl;
        return x + y;
    }
};
Foo getFoo() {
    std::cout << "getFoo()" << std::endl;
    return {};
}
int main() {
    std::cout << getFoo()(1, 2) << std::endl;
    std::cout << getFoo()[1, 2] << std::endl;
}
```

`getFoo()` is expected to be called, but clang don't call it currently
(17.0.6). This PR fixes this issue.

Fixes llvm#67976, reland llvm#68485.

- **clang/lib/Sema/SemaOverload.cpp**
- **`Sema::CreateOverloadedArraySubscriptExpr` &
`Sema::BuildCallToObjectOfClassType`**
Previously clang generate `CallExpr` for static operators, ignoring the
object argument. In this PR `CXXOperatorCallExpr` is generated for
static operators instead, with the object argument as the first
argument.
  - **`TryObjectArgumentInitialization`**
`const` / `volatile` objects are allowed for static methods, so that we
can call static operators on them.
- **clang/lib/CodeGen/CGExpr.cpp**
  - **`CodeGenFunction::EmitCall`**
CodeGen changes for `CXXOperatorCallExpr` with static operators: emit
and ignore the object argument first, then emit the operator call.
- **clang/lib/AST/ExprConstant.cpp**
  - **`‎ExprEvaluatorBase::handleCallExpr‎`**
Evaluation of static operators in constexpr also need some small changes
to work, so that the arguments won't be out of position.
- **clang/lib/Sema/SemaChecking.cpp**
  - **`Sema::CheckFunctionCall`**
Code for argument checking also need to be modify, or it will fail the
test `clang/test/SemaCXX/overloaded-operator-decl.cpp`.
- **clang-tools-extra/clangd/InlayHints.cpp**
  - **`InlayHintVisitor::VisitCallExpr`**
Now that the `CXXOperatorCallExpr` for static operators also have object
argument, we should also take care of this situation in clangd.

- **Added:**
    - **clang/test/AST/ast-dump-static-operators.cpp**
      Verify the AST generated for static operators.
    - **clang/test/SemaCXX/cxx2b-static-operator.cpp**
Static operators should be able to be called on const / volatile
objects.
- **Modified:**
    - **clang/test/CodeGenCXX/cxx2b-static-call-operator.cpp**
    - **clang/test/CodeGenCXX/cxx2b-static-subscript-operator.cpp**
      Matching the new CodeGen.

- **clang/docs/ReleaseNotes.rst**
  Update release notes.

---------

Co-authored-by: Shafik Yaghmour <[email protected]>
Co-authored-by: cor3ntin <[email protected]>
Co-authored-by: Aaron Ballman <[email protected]>