Cache cargo-udeps package in CI

[goatgoose]

Problem:

cargo-udeps started failing to build in the udeps CI job. #2592 added the --locked flag to resolve this. However, in order to use the --locked flag, cargo install was run manually without camshaft/install, because camshaft/install doesn't currently support providing arguments to cargo install. This means that the cargo-udeps build isn't cached.

Solution:

We should add support for cargo install flags to camshaft/install, and then replace the manual cargo install in the udeps CI job with camshaft/install.