add dependency validation to CI

[bcolloran]

@ericpgreen2: regarding issues like https://github.com/rilldata/rill/issues/3596 (imports from web-local into web-common), we could add something like this to CI that checks a set of dependency rules: https://github.com/sverweij/dependency-cruiser#declare-some-rules

Could also check for circular dependencies, which can be hard to notice (@AdityaHegde spotted some that I had added in a recent PR, but that can be easy to overlook, so automated checks would help)