Fix use-after-free due to destruction order (#2739)

Fix use-after-free due to destruction order (#2739)

A test for PR #2737 was failing even though the PR only added dead code.
This PR fixes the issue by fixing two use-after-free bugs:

- `ResolutionBitVectorProof` has a `Context` and a
`std::unique_ptr<BVSatProof>` member. The `BVSatProof` depends on the
`Context` and tries to access it (indirectly) in its constructor but
because the context was declared after the proof, the context was
destroyed before the proof, leading to a use-after-free in a method
called from the proof's destructor. This commit reorders the two
members.
- `TLazyBitblaster` was destroyed before the `LFSCCnfProof` in
`BitVectorProof` because `SmtEngine`'s destructor first destroyed the
theory engine and then the proof manager. This lead to a use-after-free
because `LFSCCnfProof` was using the `d_nullContext` of
`TLazyBitblaster`, which got indirectly accessed in `LFSCCnfProof`'s
destructor. This commit moves the destruction of `ProofManager` above
the destruction of the theory engine.

The issues were likely introduced by #2599. They went undetected because
our nightlies' ASAN check does not use proofs due to known memory leaks
in the proof module of CVC4.

I have tested this PR up to regression level 2 with ASAN with leak
detection disabled.