Fixes #3332. Based on previous work in #5599 and #8932.

Differences to previous PR's:

• Uses a per-port resolution
  • This prevents us from always converting to microseconds and back on ports that don't have that level of precision, no longer limiting the maximum timeout.
  • Also used to implement _thread.TIMEOUT_MAX (see CPython docs), which in turn is used to raise an OverflowError if a too large timeout is given.
• Maintains the MICROPY_PY_THREAD_LOCK_TIMEOUT feature flag from @mcdeoliveira, since some ports do not support timeouts yet.
  • Adds POSIX feature flags check since apparently my MacOS system doesn't support pthread_mutex_timedlock (see here).
  • This flag also controls the availability of _thread.TIMEOUT_MAX, which is used in the tests to determine whether timeouts are supported or the test should be skipped.
• Takes into account comments from @dpgeorge in _thread: timeout parameter is not implemented in Lock.acquire() #3332 (comment)
  • Modifies the existing mp_thread_mutex_lock to add full timeout support instead of adding an extra function.
  • Uses int64_t for the timeout value (see note below).

It still has some open issues / questions:

• The code for adding an constant float/int to the _thread class is wrong. Looking at other examples like math.PI and sys.maxsize, it looks like currently all these are defined in the global obj.h/objint.h so they can have separate implementations for each supported storage format?
  • Even nicer would be if we had some helpers / defines to make it easier to define large integer / float constants, without having to put them into the global int/float implemenation files. But that's probably out of scope for this PR.
• I've switched to int64_t because on the Unix port the max timeout would otherwise be a mere 35 minutes. However on many other ports the resolution method (see above) already allows for longer timeouts. We could add another per-port define for the type so we could use a smaller type on some ports? I'm not sure if that would be a meaningful improvement for the smaller microcontrollers.
• The TIMEOUT_MAX value is not entirely accurate; it does for example not take into account the mp_int_t size limit, or on the Unix port the fact that we cannot use the full uint32 range because the current time should be subtracted.

Feedback is welcomed!