Support allow_protocols option for catalog_protocol_usage validation

[parksb]

When catalog_protocol_usage is set to strict, any dependency not using the catalog: protocol is flagged as an error. This is a problem for dependencies using protocols like portal:, file:, or link: that serve a different purpose and can't be replaced by catalog:.

This PR adds allow_protocols option that lets users specify protocols from the catalog_protocol_usage validation.

validation:
  - workspaces: ["*"]
    rules:
      catalog_protocol_usage:
        level: strict
        allow_protocols:
          - portal:
          - file:

allow_protocols is only valid with strict or warn, and using it with optional or restrict is rejected as invalid configuration.