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

[Stefan Gränitz via cfe-commits]

weliveindetail wrote:

This should fix both: initializing the native target (your reported case) AND skipping the test on platforms that don't support JIT (other build bots complained).

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