This changes the return type of {CompileCWasmEntry} from a {MaybeHandle}
to {Handle}. All call sites used {ToHandleChecked} anyway, and if
compiling a c-wasm-entry failed, something seriously went wrong. Hence
fail immediately during compilation, instead of returning an empty
handle and then failing later.

R=jkummerow@chromium.org

Change-Id: I19d85e907670c92da74c9a7ab2d9b646682a02cd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2237133
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68279}