GLEIF enforcement logic for institutions POST/PUT operations

[PatrickGoRaft]

Use the GLEIF API to validate LEIs of entities registering with the HMDA Platform. If an LEI returns a status other than Valid, it should not be registered.

[nongarak]

The validation should check that the LEI exists in GLEIF (is a "valid" LEI). Beyond that, if we can enforce that new entities registering with the Platform return a GLEIF RegistrationStatus NOT IN (DUPLICATE, RETIRED, ANNULLED, CANCELED), that would be even more ideal. Whether the LEI later takes one of those statuses is an issue for reg compliance, but we shouldn't allow institutions to sign up initially using deprecated LEIs.

Whether we allow institutions to sign up using LEIs with a RegistrationStatus of LAPSED is another question - these are technically valid LEIs that have not been deprecated as a bad status, but could be stale information as they are not updating the data with GLEIF. I'll defer to @Kibrael on that one.

[Kibrael]

Let's go with the minimum requirements for Valid at this point and we can investigate Reg C requirement clarifications in the future.

[PatrickGoRaft]

Include a flag or some other logic to allow test institutions to be added*