Add tests for setting and deleting attributes defined in C

CPython defines 375 attributes with PyMemberDef and PyGetSetDef (excluding the _test* modules), but the test suite never assigns to 187 of them and never deletes 332 of them.

Deletion in particular is almost untested, although it is a separate code path: the setter is called with NULL, and an implementation which does not expect this crashes or leaves the object in a broken state.

Three bugs found this way are gh-156099, gh-156100 and gh-156101; gh-152817 is another one.

The following PR adds writing and deleting tests for each writable attribute.

Linked PRs

• gh-156107
• gh-156184
• gh-156191

首先定位 CPython 中针对使用 PyMemberDef 和 PyGetSetDef 定义的属性的测试覆盖情况。检查当前如何赋值和删除可写属性，然后利用已报告的缺口和现有测试覆盖每个可写属性。完成标准是：所有可写属性的赋值和删除都经过测试，且不会发生崩溃或对象损坏。