gh-74690: Optimise isinstance() and issubclass() calls against runtime-checkable protocols by avoiding costly super() calls

[AlexWaygood]

Before:

>python -m timeit -s "from typing import SupportsIndex" "isinstance(0, SupportsIndex)"
Running PGUpdate|x64 interpreter...
1000000 loops, best of 5: 379 nsec per loop

>python -m timeit -s "from typing import SupportsIndex" "issubclass(int, SupportsIndex)"
Running PGUpdate|x64 interpreter...
500000 loops, best of 5: 592 nsec per loop

After:

>python -m timeit -s "from typing import SupportsIndex" "isinstance(0, SupportsIndex)"
Running PGUpdate|x64 interpreter...
1000000 loops, best of 5: 298 nsec per loop

>python -m timeit -s "from typing import SupportsIndex" "issubclass(int, SupportsIndex)"
Running PGUpdate|x64 interpreter...
500000 loops, best of 5: 523 nsec per loop

Timings done using a fresh PGO-optimised build on Windows with the main branch.

• Issue: Performance of typing._ProtocolMeta._get_protocol_attrs and isinstance #74690

[AlexWaygood]

For comparison, here's the timings against "normal" classes... we're still some way off 🙃 A lot closer than we were in 3.11, though.

>python -m timeit "isinstance(0, int)"
Running PGUpdate|x64 interpreter...
10000000 loops, best of 5: 27.4 nsec per loop

>python -m timeit "issubclass(str, int)"
Running PGUpdate|x64 interpreter...
10000000 loops, best of 5: 34.6 nsec per loop