This CL extracts the classes CompilationHelper, InstantiationHelper,
and AsyncCompileJob from wasm-module.cc and puts them into
module-compiler.{h|cc}. This is necessary to introduce a
WasmCompilationManager which is known to the isolate and manages the
lifetime of all AsyncCompileJobs.

In addition to the mechanical changes of copying the code and splitting
class declaration from instantiation, I did the following changes:

* I renamed the CompilationHelper to ModuleCompiler.
* A finalizer function is passed to the InstantiationHelper as a
  parameter.
* Adjusted UpdateDispatchTable in wasm-module.cc to make it available in
  wasm-module.h, also with the internal signature.
* Duplicate the ResolvePromise/RejectPromise helper functions.

I did not rename InstantiationHelper because I could not come up with a
good name, and it could benefit from a small special refactoring anyways.

BUG=v8:6436
R=clemensh@chromium.org, mtrofin@chromium.org

Change-Id: I4abe854c36dfc995b34c9d7b3e7ec0f4f0aa562e
Reviewed-on: https://chromium-review.googlesource.com/525572
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Mircea Trofin <mtrofin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45773}