Run `uv-dev` tests (#11618)
In #6827, we switched the uv-dev binary to not being built by default.
As an unintended side effect, we were also stopping to run the tests
that ensured the schema was up-to-date.
To fix this, we split uv-dev into an unconditional library, with only
the binary being a conditional build. This way, `cargo test` and `cargo
nextest` pick those tests up again.
An alternative would be running tests with the `dev` feature, with the
side effect of always building the uv-dev binary, too.
