Run more resource-intensive regression tests somewhere

[chameco]

We've historically used our "production" proofs in CI as regression tests. Some of these proofs (BLST, see #1622; maybe BIKE, see #1563) require enough time or memory that they are unwieldy to run in normal CI on every commit. However, it would still be useful to see if future SAW changes negatively impact these proofs. We should run these proofs regularly somewhere (maybe daily on master in Fryingpan?) and make sure that the results are visible.

[jldodds]

Proposed approach, discussed by most caretakers:

• Add a dev branch with automatic merge to main when full CI succeeds
• Split CI into integration tests and proof tests
• Integration tests run on every commit for every branch
• Proof tests run nightly on dev branch on Galois runners kicked off from actions (could be parallelized to speed up)
• Social agreement that it is acceptable to roll back dev branch to last fully working commit if breaking commit is blocking progress
• Apply continual effort to continue to expand integration tests to minimize the need for proof tests