Policy: KAS registry URI validation is invalid

[jrschumacher]

KAS registry URI validation is invalid

./dsp tructl policy kas-registry create -u "https://local-dsp.virtru.com:8080/kas" -r "https://local-dsp.virtru.com:8080/kas/v2/kas_public_key"
Using profile [local]
   ERROR    Failed to create Registered KAS entry: rpc error: code = InvalidArgument desc = validation error:                                                                                                                                                 
             - public_key.remote: URI must be a valid URL (e.g., 'https://demo.com/') followed by additional segments. Each segment must start and end with an alphanumeric character, can contain hyphens, alphanumeric characters, and slashes. [uri_format]

Acceptance Criteria

• update the validation to use buf's this.Uri()

[jrschumacher]

This will be closed with #1656