Add composable scenario tests for signer using madhouse

[moodmosaic]

Adds madhouse-based scenario testing to signer.

Provides reusable, DRY test steps that can be composed into scenarios.

First example:

scenario![
    test_context,
    CreateFailedDkgShares,
    WriteDkgShares,
    VerifyDkgVerificationFailed,
];

Based on property-based state machine testing (see spec).

[moodmosaic]

/cc @cylewitruk

[cylewitruk]

Will look more closely later, just tossing out a couple of quick comments on the dependency handling.

This repo has the convention of defining all dependencies in the workspace Cargo.toml, where dependencies in the [dependencies] stanza (i.e. full dependencies) are always specified with default-features = false with explicit feature enablement.

You'll also need to cargo vet and handle the dependency diffs.

[BowTiedRadone]

@cylewitruk: It seems no vetting is needed after moving madhouse-rs to dev dependencies. cargo vet output:

$ cargo vet
Vetting Succeeded (147 fully audited, 4 partially audited, 559 exempted)
 WARN Your supply-chain has unnecessary exemptions which could be relaxed or pruned.
 WARN   Consider running `cargo vet prune` to prune unnecessary exemptions and imports.

[MCJOHN974]

@cylewitruk: It seems no vetting is needed after moving madhouse-rs to dev dependencies. cargo vet output:

Try to run cargo vet prune and it should fix problems

[BowTiedRadone]

That worked @MCJOHN974 🙏

$ cargo vet
Vetting Succeeded (151 fully audited, 4 partially audited, 555 exempted)

@moodmosaic considering cargo vet is clean should we consider taking this PR out of draft?

[moodmosaic]

/cc @cylewitruk @djordon @aldur — are you interested in this? Should I keep open for a longer time?