ci: Investigate crane

[justinrubek]

CI actions are commonly taking 15+ minutes.

The time spent is mostly compiling crates, with each crate being compiled fresh for each run.

Crane uses nix to cache cargo dependencies from the project separately from the crates being developed on and avoids rebuilding unchanged dependencies between invocations.

Using crane could significantly reduce CI times (assuming we also add a cache for this).

Crane also has facilities for checks using clippy, rustfmt, and cargo-tarpaulin.

A solution would replace packages built with rustPlatform.buildRustPackage with craneLib.buildPackage and craneLib.buildDepsOnly.
Additionally, craneLib.cargoClippy and craneLib.cargoFmt are desirable (see #40).

If the packages can be built using a shared cargoArtifacts then it should be trivial to persist the artifacts in cachix.

[justinrubek]

Done and merged in PR #126 and #121