[clang] [libclang] Add clang_CXXMethod_getQualifiers, clang_Cursor_isConstexpr, and clang_CXXMethod_isExplicitObjectMemberFunction (PR #183305)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> Apologies for the long delay, but @Endilll and I were finally able to meet to discuss this PR in more detail during a 1:1 today.

I know there are a few more PRs for libclang which are outstanding. Vlad and I are planning to review those as well, but I've got WG14 meetings coming up that take precedence, so it might be Sept before we get on #183504 and #134551. If there are other libclang PRs that are stalled, it'd be good to let us know so we can try to get them as well.

https://github.com/llvm/llvm-project/pull/183305