Add test to ensure every table update has corresponding `_apply_table_update` function

[kevinjqliu]

Pre-req: #822. This test will fail until #822 is merged

While looking at #864 and #950, I noticed that some TableUpdate classes do not have corresponding _apply_table_update function. I think we should enforce this in tests so that any future TableUpdate have the necessary _apply_table_update to process the update.

Example

This test currently fails since RemoveSnapshotRefUpdate and RemoveSnapshotsUpdate both are missing corresponding _apply_table_update function.

Run: poetry run pytest tests/table/test_init.py::test_table_update_have_corresponding_dispatch

================================================================== FAILURES ==================================================================
_______________________________________________ test_table_update_have_corresponding_dispatch ________________________________________________

    def test_table_update_have_corresponding_dispatch() -> None:
        from pyiceberg.table import TableUpdate, _apply_table_update
    
        # every TableUpdate class should have corresponding `_apply_table_update` dispatch function
        table_update_class = set(TableUpdate.__origin__.__args__)  # type: ignore
        dispatch_function_class = set(_apply_table_update.registry.keys())
        missing_dispatch_function = table_update_class - dispatch_function_class
>       assert len(missing_dispatch_function) == 0, f"Missing dispatch function for {missing_dispatch_function}"
E       AssertionError: Missing dispatch function for {<class 'pyiceberg.table.RemoveSnapshotRefUpdate'>, <class 'pyiceberg.table.RemoveSnapshotsUpdate'>}
E       assert 2 == 0
E        +  where 2 = len({<class 'pyiceberg.table.RemoveSnapshotRefUpdate'>, <class 'pyiceberg.table.RemoveSnapshotsUpdate'>})

tests/table/test_init.py:1166: AssertionError
========================================================== short test summary info ===========================================================
FAILED tests/table/test_init.py::test_table_update_have_corresponding_dispatch - AssertionError: Missing dispatch function for {<class 'pyiceberg.table.RemoveSnapshotRefUpdate'>, <class 'pyiceberg.table.RemoveSnapshots...