More gil-disabled type thread safety

[DinoV]

Bug report

Bug description:

Some areas of typeobject are still not thread safe after fixing mro. Those at least include:

• tp_flags - most of these that change at runtime are probably protected by locks after MRO (e.g. Py_TPFLAGS_VALID_VERSION_TAG and various flags set while readying). But at least some get modified outside of the lock still (e.g. Py_TPFLAGS_IS_ABSTRACT, Py_TPFLAGS_SEQUENCE and Py_TPFLAGS_MAPPING via the abc module). These should maybe all be atomic and/ors or protected by the same type lock.
• tp_watched - also needs atomic and/or in PyType_Watch and PyType_Unwatch

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

[kumaraditya303]

tp_flags - most of these that change at runtime are probably protected by locks after MRO (e.g. Py_TPFLAGS_VALID_VERSION_TAG and various flags set while readying). But at least some get modified outside of the lock still (e.g. Py_TPFLAGS_IS_ABSTRACT, Py_TPFLAGS_SEQUENCE and Py_TPFLAGS_MAPPING via the abc module). These should maybe all be atomic and/ors or protected by the same type lock.
tp_watched - also needs atomic and/or in PyType_Watch and PyType_Unwatch

I think both of the issues are fixed now:

1. the type slot thread safety fixed the thread safety of tp_flags. gh-127266: avoid data races when updating type slots v2 #133177
2. PyType_Watch is now documented to be thread unsafe. gh-131544: Update docs for PyType_AddWatcher #132015

[kumaraditya303]

Closing as it is fixed on main branch.