py: boolean-mask keys raise NotImplementedError, not TypeError

h5py supports boolean masks for reads and writes; clawhdf5 supports
neither, so a mask is an unsupported operation (NotImplementedError, as
for every other edit the bindings cannot do), not an invalid key.

Tests: test_unsupported_edits_are_clear_errors (1-D, N-D and per-axis
mask writes, file unchanged) and test_boolean_masks_are_refused (reads).

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

CHANGELOG.md

@@ -98,6 +98,8 @@
     compound fields by name, variable-length data, ...;
     `docs/known-issues.md`).
 - `File.mode`, `File.flush()` (a no-op), `Dataset.chunks`.
+- Boolean-mask keys (`ds[mask]`, `ds[mask] = v`), which h5py supports,
+  raise `NotImplementedError` (they raised `TypeError`).
 - Tests (`tests/test_edit.py`): each edit applied to two copies of a file,
   by h5py and by clawhdf5, and both read back through h5py after every
   edit, on files h5py writes with `libver` earliest, v114 and latest and on