Improve test_capi.test_structmembers

[serhiy-storchaka]

test_capi.test_structmembers tests writing and reading attributes that represent C struct members (defined via PyMemberDef). But for most types it only tests 1 or 2 valid values, and maybe yet 1 or 2 values that trigger a RuntimeWarning, for some types. It does not test integer overflow errors. It does not test integer-like objects which are not instances of int (and the range of accepted values is different for such objects due to quirks of implementation). Some bugs (like #114388, but I'll open more issues for other bugs or quirks) are slipped unnoticed.

I'm going to add support for more C types, so I need more comprehensive tests. The proposed PR unifies tests for integer members. It contains some special cases which will be removed when the implementation for integer members be fixed and unified.

Linked PRs

• gh-114392: Improve test_capi.test_structmembers #114393
• [3.12] gh-114392: Improve test_capi.test_structmembers (GH-114393) #115010
• [3.11] gh-114392: Improve test_capi.test_structmembers (GH-114393) #115030