Support custom `ci` Cargo profile.

[xStrom]

Something like:

[profile.ci]
inherits = "dev"
debug = 0 # Don't compile debug info to reduce compilation artifact size for cache benefits.
[profile.ci.package."*"]
debug-assertions = true # Keep always on for dependencies for cache reuse.

Should probably detect whether it exists and run with dev if it doesn't.

Worth having some sort of ci-test profile for optimized builds for slow runtime tests?