This PR fixes the bug that `collectAxioms` didn't collect axioms
referenced by other axioms. One of the results of this bug is that
axioms collected from a theorem proved by `native_decide` may not
include `Lean.trustCompiler`.
Closes#8840.
This PR adds configuration options for
`decide`/`decide!`/`native_decide` and refactors the tactics to be
frontends to the same backend. Adds a `+revert` option that cleans up
the local context and reverts all local variables the goal depends on,
along with indirect propositional hypotheses. Makes `native_decide` fail
at elaboration time on failure without sacrificing performance (the
decision procedure is still evaluated just once). Now `native_decide`
supports universe polymorphism.
Closes#2072
