feat(v1.30.1): retrieve users' last login time and preview API keys

[bevzzz]

What is changed?

This PR adds optional includeLastUsedTime parameter to users.db.byName and users.db.listAll methods, which controls if the last login time will be retrieved for the users.

Additionally, UserDB model has 2 new fields:

• createdAt: returned for all users (provided server is v1.30.1 and above)
• apiKeyFirstLetters: returned whenever request is made by the cluster admin (intended to be displayed in the WCS Console)

Updated openapi.ts schema spec.

TODO

• [x] Run tests with v1.30.1