[Spike] Streamline / Automate onboarding and offboarding process

### User Story

As a product manager / lead, I want to onboard and offboard members efficiently , so that the process is faster for everyone.

### Description

Initially, we had a Google sheet for new members to fill out, a single GitHub issue for all onboarding, and another single GitHub issue for offboarding.

There are redundancies and repetition that should be eliminated for both management and new members.

Additionally, there should be a single source of tracking for each member onboarding and offboarding.

Ideally, we would automate permissioning (adding to GitHub teams, inviting to the proper Slack channels, updating the roster, etc.)

### Acceptance Criteria

- [x] Research approaches on how we can improve on our onboarding/offboarding process.
- [x] Design the workflows involved.
- [ ] Present findings to product and leads.

### Design References

_No response_

### Technical References

_No response_

### Additional Information

_No response_