Add integration tests for licenses

## Assert the following abilities:
### Licenses work end to end:
Create a bundle library, `Settings.bundle` to exemplify end to end usage and validate such usage.

### Transitive license propagation of licenses for all cases

Consider the following case: A pod, `Foo` has a subspec `Bar`. `Bar` depends on the external pod, `Baz`. Ensure that when a user depends on `//Foo:Bar`, that the license of `Baz` is correctly propagated.

The tests should run on the CI.