Port a3776a63

Original Commit Message:

    Backends do not care about the concrete type, they only need to know the
    "kind" (e.g. "ref" or "i32").
    In order to prepare Liftoff to use the value kind instead of the
    value type for all stored data, this CL moves the kind out of the
    ValueType and makes it a top-level enum.

R=clemensb@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: Ia4111941313037aa1a77f2a0a1536d492ae9dc0b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2712392Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#72915}