Add db unavailable error and add orgID to db models

[daniellemaxwell]

Scope of changes

Adds an Unavailable error to the Tenant db. An organization ID has been added to the Member, Project, and Topic db models as well. TODOs have been created to add orgID validation to the validation methods.

Fixes SC-13086

Type of change

• new feature
• bug fix
• documentation
• testing
• technical debt
• other (describe)

Acceptance criteria

Describe how reviewers can test this change to be sure that it works correctly. Add a checklist if possible.

Author checklist

• I have manually tested the change and/or added automation in the form of unit tests or integration tests
• I have updated the dependencies list
• I have recompiled and included new protocol buffers to reflect changes I made
• I have added new test fixtures as needed to support added tests
• Check this box if a reviewer can merge this pull request after approval (leave it unchecked if you want to do it yourself)
• I have moved the associated Shortcut story to "Ready for Review"

Reviewer(s) checklist

• Any new user-facing content that has been added for this PR has been QA'ed to ensure correct grammar, spelling, and understandability.
• Are there any TODOs in this PR that should be turned into stories?

[shortcut-integration]

This pull request has been linked to Shortcut Story #13086: Add Unavailable status code to db.go Get (TODO on lines 164-165) and Put (TODO on lines 203-204) methods and add orgID to db models..

[bbengfort]

Looks great!