Rework locks

[bugadani]

• Move locks to a new module
• Deduplicate implementation
• Reimplement critical_section in terms of Lock
• Make Lock reentrant by default

This change should prevent multi-core apps spinning in interrupt-free context if the other core is holding the global lock.

It's hardly a stress test, but I've ran the multicore examples on an ESP32 and they worked as expected.

[bugadani]

Fun fact: this PR came 2 days before #797 turned one year old :D

[MabezDev]

Fun fact: this PR came 2 days before #797 turned one year old :D

I expect you to mark this occasion in your calendar for next year too :D

[bjoernQ]

Nice!

[MabezDev]

LGTM, I'm glad we're reusing code for both the stand alone lock and CS now.

It would be nice to have a test or two, but we can leave that for now. One final thing to consider before merging, what about naming the lock module sync instead?

[bugadani]

One final thing to consider before merging, what about naming the lock module sync instead?

It's private, we can deal with this later, when we're fixing the fallout from this 🤣