Buffer refactor

[approxit]

What I've done:

• Refactored whole buffer and scoring buffer from golem.managers.proposals.plugins
• Introduced composable buffers - simple buffer / background fill / expiration
• Introduced Waiter to take the heavy lifting from simple buffer
• Introduced SingleUseSemaphore to take the heavy lifting from bacground fill buffer
• Moved asyncio related stuff from golem.utils to single name space golem.utils.asyncio, as stuff started to be mixed with other utils
• Tests for coverage
• Reformatted the code

Notable remarks:

• Low level asyncio is tricky, but quite fun to play around :D
• SimpleBuffer covers quite fully functionality from ErrorReportingQueue, I would remove the second one in favor of the first, but team have different opinions about this, so it will be left as is
• PR will be changed from draft after ray-on-golem testing session

[approxit]

In addition to main PR descriptions, here are more stuff done:

• Fixed some log lines to use % instead of f-strings.
• Use cancel_and_await/cancel_and_await_many when applicable.
• Renamed Buffer plugin to BufferPlugin from managers level
• Fixed checks, which require some lib upgrades, and also fix version of python
• Added python 3.12 in CI
• Fix python 3.12 checks complaints

[approxit]

And another update:

• Demand and Proposal resources got new method to get their expiration dates
• RefreshingDemandManager uses deamnd's expiration date instead of misused property
• Buffer got remixed interface to support race conditions in buffer composition.

[shadeofblue]

whew... that's a lot of code ... I don't feel I have finished the review and probably it would be good to touch base on a call anyway but here are some comments that I have had...

[shadeofblue]

please see my comments... otherwise, lgtm afaict

[shadeofblue]

why "not below" instead of "above"?

Suggested change

	"Proposals count %d is not below minimum size %d, skipping fill",
	"Proposals count %d is above minimum size %d, skipping fill",