[clang] [clang-repl] Expose CreateExecutor() and ResetExecutor() in extended Interpreter interface (PR #84460)

[Stefan Gränitz via cfe-commits]

weliveindetail wrote:

This PR was factored out for isolated review and to reduce the size of the follow-up patch in https://github.com/llvm/llvm-project/pull/84461. It depends on the previous change in https://github.com/llvm/llvm-project/pull/83126. Combined patch size will shrink significantly, once it landed (tonight hopefully). Until then please refer to the single commit https://github.com/llvm/llvm-project/pull/84460/commits/023cab5a10e381533c9dc2a7c15823bb9bb9e54e

https://github.com/llvm/llvm-project/pull/84460