Validate alphabet strategies

[Zac-HD]

Closes #3503; also fixes #3500 and fixes #3504.

[honno]

Work on array_api.py things and handling multi-char alphabet strategies looks great!

Fix for escalation.py works, however on my end this reveals a new problem when using Aaron's #3504 reproducer (with numpy==1.23.0).

$ pytest test.py
...
exception = IndexError('index 0 is out of bounds for axis 0 with size 0')

    def get_interesting_origin(exception):
        # The `interesting_origin` is how Hypothesis distinguishes between multiple
        # failures, for reporting and also to replay from the example database (even
        # if report_multiple_bugs=False).  We traditionally use the exception type and
        # location, but have extracted this logic in order to see through `except ...:`
        # blocks and understand the __cause__ (`raise x from y`) or __context__ that
        # first raised an exception as well as PEP-654 exception groups.
        tb = get_trimmed_traceback(exception)
>       filename, lineno, *_ = traceback.extract_tb(tb)[-1]
E       IndexError: list index out of range
...
FAILED test.py::test - IndexError: list index out of range

Looks to be a similar problem as before, where we aren't handling tb=None and therefore len(traceback.extract_tb(tb))=0.

hypothesis/hypothesis-python/src/hypothesis/internal/escalation.py

Line 114 in 9f5b69e

filename, lineno, *_ = traceback.extract_tb(tb)[-1]

[Zac-HD]

🤦‍♂️ ah, yep, I just had a too-old version of Numpy in my venv. Fixing that made the repro work; and now we have a complete fix and corresponding test.