Systems: When fetching allow for filtering on systems for which credentials have or have not been registered.

[scblack321]

One use case is to allow a UI to show appropriate systems when launching an application.

[scblack321]

Proposed design:
Add a query parameter for the getSystems endpoint.
Parameter name filterByCredentials
Parameter type ENUM with values ANY, NO_CREDENTIALS, WITH_CREDENTIALS
Default is ANY

[scblack321]

Query parameter would be supported by the getSystems endpoint, but would not be supported for the dedicated search endpoints.

[scblack321]

Might be better to first update Systems so that we persist information about which credentials have been registered for each system. We already have some of this information in the table systems_login_user.
One option is to extend this table to include all credential registration information.
Of course excluding the actual credentials.
Since we always need to check this table when looking up credentials, this might provide a natural way to lazily fill in the credential registration info for systems with credentials registered prior to this update.
Having this info in a Systems table should make it simpler and faster to:

• filter by credentials
• allow for fetching of credential registration info by system
• allow for fetching of credential registration info by Tapis user