Strict mode: fail on unused imports

[anderseknert]

Running opa check with the --strict flag currently fails when unused assignment is encountered. It would be a good addition if we added a new check to similarly fail on unused imports:

package foo

import data.foo.x

allow {
    input.foo == "bar"
}

$ opa check --strict foo.rego
1 error occurred: policy.rego:3: rego_compile_error: import data.foo.x unused

Whoever wants to work on this might be helped by taking a look at this strict mode PR forbidding the use of input and data as identifiers in rules and variables.

[damienjburks]

Hey y'all! I'd love to take on this issue.

[anderseknert]

Good to see you back @damienjburks! Go right ahead, and holler out if you need any support :)