[clang] [NFC][Clang][Interp] Rename `clang::interp::State::getCtx` to `clang::interp::State::getASTContext` (PR #106071)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr approved this pull request.

LGTM if the CI comes back green, but we use "[clang][bytecode]" (all lowercase) in the commit message now.

https://github.com/llvm/llvm-project/pull/106071