Backport Proof of Space perf improvements from abundance

[teor2345]

This PR backports the latest compatible Proof of Space changes from abundance, including some API refactors, including all relevant files up until commit:
nazar-pc/abundance@6d56b48

It should be reviewed one commit at a time.
The copied code is best reviewed by:

• checking out abundance at that commit
• copying across the code from abundance
• checking there are no differences

The copied code includes:

• ab-proof-of-space replacing subspace-proof-of-space
• ab-chacha8 copied into shared
• SolutionPotVerifier trait from ab-core-primitives

Various minor fixes are then made to get it to compile and pass CI:

• Cargo.toml build files
• imports
• incompatibilities
• revert dependency and compiler changes we haven't updated to yet
• clippy fixes
• missed docs

Code contributor checklist:

• I have read, understood and followed contributing guide

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[teor2345]

The benchmark failure might take some time to fix, and I've run out of time today. Looks like the benchmarks expect Proof of Space to return Ok, but instead it's returning an error.

The "check individually" failure is trivial, just some missing dead code annotations.

[nazar-pc]

Note that miri annotations may not be necessary since this repo doesn't run tests under Miri (abundance does to have additional guarantees that unsafe code maintains invariants, but some tests are too slow to run regularly in CI or impractical to run in general, hence corresponding annotations).

Similarly no-panic ensures compiler can figure out the code can't possibly panic at compile time, which allows for better optimizations, but this repo doesn't run corresponding tests, so not sure how useful it is to port over.