Allow setting thread attributes/stack size (and name)

[PallHaraldsson]

In a portable way, e.g. calling pthread_attr_setstacksize

https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p2019r8.pdf

#52707 (comment)

See e.g. this library, might be helpful:

https://ztdthread.readthedocs.io/en/latest/