dataclasses: make sure inherited classes have correct frozenness

[matthiasdiener]

Without this, code would fail with optimizations enabled:

$ python -O ../grudge/examples/wave/wave-op-mpi.py
Traceback (most recent call last):
  File "/Users/mdiener/Work/enew/pytato/../grudge/examples/wave/wave-op-mpi.py", line 41, in <module>
    import grudge.op as op
  File "/Users/mdiener/Work/enew/grudge/grudge/op.py", line 109, in <module>
    from grudge.reductions import (
  File "/Users/mdiener/Work/enew/grudge/grudge/reductions.py", line 83, in <module>
    from grudge.array_context import MPIBasedArrayContext
  File "/Users/mdiener/Work/enew/grudge/grudge/array_context.py", line 41, in <module>
    from meshmode.array_context import (
  File "/Users/mdiener/Work/enew/meshmode/meshmode/array_context.py", line 1255, in <module>
    from pytato.analysis import PytatoKeyBuilder
  File "/Users/mdiener/Work/enew/pytato/pytato/__init__.py", line 50, in <module>
    import pytato.analysis as analysis
  File "/Users/mdiener/Work/enew/pytato/pytato/analysis/__init__.py", line 36, in <module>
    from pytato.array import (
  File "/Users/mdiener/Work/enew/pytato/pytato/array.py", line 913, in <module>
    @array_dataclass()
     ^^^^^^^^^^^^^^^^^
  File "/Users/mdiener/Work/enew/pytato/pytato/array.py", line 318, in map_cls
    dc_cls = dataclasses.dataclass(init=True, frozen=__debug__,
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/mdiener/Work/enew/miniforge3/envs/ceesd/lib/python3.12/dataclasses.py", line 1265, in wrap
    return _process_class(cls, init, repr, eq, order, unsafe_hash,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/mdiener/Work/enew/miniforge3/envs/ceesd/lib/python3.12/dataclasses.py", line 1024, in _process_class
    raise TypeError('cannot inherit non-frozen dataclass from a '
TypeError: cannot inherit non-frozen dataclass from a frozen one

Followup of #521.

[inducer]

I'm generally OK with this, if the issues are resolvable.