sorts: make recursive_insertion_sort generic over Comparable items

[Rokesh2008]

Part of #15234

This is an in-place sort, so it follows the MutableSequence[T] bucket of the Comparable/TypeVar convention discussed on #15234, rather than the Iterable[T] -> list[T] bucket used by copy-and-return sorts:

• rec_insertion_sort/insert_next now take MutableSequence[T] bound to Comparable
• rec_insertion_sort now returns the sorted collection (previously -> None) and n defaults to len(collection), so it can be called with a single argument — needed so it fits the shared SORTS battery in tests/test_sorts.py, which calls every sort as sort(list(case))
• added a string doctest alongside the existing int examples
• registered rec_insertion_sort in the shared SORTS battery (checked against sorted(), including the Person/Dog comparable objects) and in test_sort_rejects_non_comparable_items

Tests:

• python -m doctest -v sorts/recursive_insertion_sort.py — 18/18 passed
• Verified rec_insertion_sort against every case in tests/test_sorts.py's CASES tuple with a single-argument call, matching sorted()
• Confirmed rec_insertion_sort([1, "a"]) raises TypeError

Linking with Part of #15234 rather than a closing keyword, per the issue's contribution guidance.

[cclauss]

ON HOLD: Our focus is on merging or closing old pull requests before October 1st.

• https://hacktoberfest.com

[Rokesh2008]

Pushed a follow-up fix per review feedback:

• rec_insertion_sort(collection, n) is back to a required n and a pure None return — no more optional n and no returning the collection, so the in-place API contract is unchanged.
• Kept the Comparable/TypeVar generic typing (using a plain TypeVar("T", bound=Comparable) rather than PEP 695 syntax, to match the file's existing style).
• Kept the string doctest alongside the int ones.
• Since rec_insertion_sort no longer returns a value, it no longer fits the shared SORTS battery in tests/test_sorts.py (which asserts on the return value), so I removed it from that tuple and added a dedicated test_rec_insertion_sort (parametrized over the same CASES, calling it in place and checking against sorted()) plus its own non-comparable-items rejection test.

Ran python -m doctest -v sorts/recursive_insertion_sort.py (21/21 passed) and the full tests/test_sorts.py suite (244 passed) locally against this branch.

[cclauss]

Based on the failing tests, I would suggest running:
% ruff rule UP047 # To see why it is complaining.
% ruff check --select=UP047 --fix --unsafe-fixes # To fix it.