Document Rollout Strategy for new AuthZ Technical Design

[arnejduranovic]

User Story

As a user of RS endpoints,
I want a smooth transition to the new auth,
so that my business operations are not disrupted

Description/Use Case

This ticket is to create a migration/rollout plan for the new AuthZ design defined in #16815 and #16816. The following questions should be addressed in detail:
- Which endpoints will need to be updated? How will they be updated/what changes are needed?
- Will RS support multiple auth methods at first, and how and for how long?
- How does the Auth MicroService play a role? Does it need to be deployed first?
- What does this migration look like from the sender/receiver/RSReact side? -- create preliminary user documentation!
- What old code will need to be deleted and how/when?

Risks/Impacts/Considerations

• May need to update previous design decisions if they are preventing a reasonable migration plan

Dev Notes

Acceptance Criteria

• Migration/rollout plan created and approved by:
  • @arnejduranovic
  • @chris-kuryak