Moved the compilation/instantiation pipeline to work off the
module object (JSObject), making the compiled module data (the
FixedArray) an implementation detail. This:
- simplifies the code by removing duplicate decode->compile->instantiate
sequences
- sets up the stage for "dressing up" the runtime model with
stronger typed APIs
- helps relanding this CL: https://codereview.chromium.org/2305903002/.
  It turns out that GCs during the cloning/instantiation events cause
trouble, and centering the source of truth on the module object helps
address this issue.

In the process, clarified cctest setup for wasm-capable isolates,
and changed signatures for consistency (using ModuleOrigin througout).

BUG=

Review-Url: https://codereview.chromium.org/2320723005
Cr-Commit-Position: refs/heads/master@{#39360}