Maintenance mode: Migrate Fleet database while continuing to pass host logs to log destination

[lukeheath]

Goal

User story
As a Fleet systems administrator,
I want to migrate Fleet's database to the latest version without bringing the Fleet server offline
so I can continue to pass host logs to my log destinations during the migration.

Changes

Product

• UI changes: TODO
• CLI usage changes: TODO
• REST API changes: TODO
• Permissions changes: TODO
• Outdated documentation changes: TODO
• Changes to paid features or tiers: TODO

Engineering

• Database schema migrations: TODO
• Load testing: TODO

ℹ️  Please read this issue carefully and understand it. Pay special attention to UI wireframes, especially "dev notes".

Context

• Requestor(s): @lukeheath

QA

Risk assessment

• Requires load testing: TODO
• Risk level: Low / High TODO
• Risk description: TODO

Manual testing steps

1. Step 1
2. Step 2
3. Step 3

Testing notes

Confirmation

1. Engineer (@____): Added comment to user story confirming successful completion of QA.
2. QA (@____): Added comment to user story confirming successful completion of QA.

[noahtalerman]

Heads up @lukeheath and @pintomi1989, this air guitar was brought to feature fest on 2024-02-15 and wasn't prioritized for the current design sprint.