We unify the implementation of element segment expression entries with
other initializer expressions: we represent them with a {WireBytesRef}
and decode them with {InitExprInterface}. Except for reducing code
duplication, this also fixes a bug where {global.get} entries in element
segments could reference invalid globals.

Changes:
- Change {WasmElemSegment::Entry} to a union of a {WireBytesRef}
  initializer expression and a {uint32_t} function index.
- In module-decoder, change parsing of expression entries to use
  {consume_init_expr}. Add type checking to
  {consume_element_func_index}, to complement type checking happening in
  {consume_init_expr}.
- In module-instantiate.cc:
  - Move instantiation of indirect tables before loading of element
    segments. This way, when we call {UpdateDispatchTables} in
    {SetTableEntry}, the indirect table for the current table will also
    be updated.
  - Consolidate table entry instantiation into {SetTableEntry}, which
    handles lazily instantiated functions, or dispatches to
    {WasmTableObject::Set}.
  - Rename {InitializeIndirectFunctionTables} to
    {InitializeNonDefaultableTables}.
  - Change {InitializeNonDefaultableTables} and {LoadElemSegmentImpl}
    to use {EvaluateInitExpression}.
- Add a test to exclude mutable/non-imported globals from the element
  section.
- Update tests as needed.
- Update .js module emission in wasm-fuzzer-common.

Change-Id: I29c541bbca8531e8d0312ed95869c8e78a5a0c57
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3364082Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78476}