[wasm][gc] Test wasm code gc as part of "--future"

This stages wasm code gc behind "--future" to get test coverage while
implementing this feature.

R=mstarzinger@chromium.org

Bug: v8:8217
Change-Id: Id620ee92518c4dd9cebc0fd47817bfc80e5cf3f5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1559741
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60722}

src/flag-definitions.h

@@ -690,6 +690,7 @@ DEFINE_NEG_IMPLICATION(wasm_interpret_all, asm_wasm_lazy_compilation)
 DEFINE_NEG_IMPLICATION(wasm_interpret_all, wasm_lazy_compilation)
 DEFINE_NEG_IMPLICATION(wasm_interpret_all, wasm_tier_up)
 DEFINE_BOOL(wasm_code_gc, false, "enable garbage collection of wasm code")
+DEFINE_IMPLICATION(future, wasm_code_gc)
 
 // Profiler flags.
 DEFINE_INT(frame_count, 1, "number of stack frames inspected by the profiler")