Remotely install/remove Fleet Desktop on host

[getvictor]

Goal

User story
As an IT service desk rep,
I want to push Fleet Desktop to a user's machine (the host already has fleetd w/o Desktop)
so that they can install some special software.

Key result

Original requests

Context

This is a potential future feature. It came up during discussions of #25924

• Product designer: _________________________

Changes

Product

• UI changes: TODO
• CLI (fleetctl) usage changes: TODO
• YAML changes: TODO
• REST API changes: TODO
• Fleet's agent (fleetd) changes: TODO
• GitOps mode changes: TODO
• Activity changes: TODO
• Permissions changes: TODO
• Changes to paid features or tiers: TODO
• Transparency changes: TODO
• First draft of test plan added
• Other reference documentation changes: TODO
• Once shipped, requester has been notified
• Once shipped, dogfooding issue has been filed

Engineering

• Test plan is finalized
• Feature guide changes: TODO
• 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".

QA

Risk assessment

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

Test plan

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

Testing notes

Confirmation

1. Engineer: Added comment to user story confirming successful completion of test plan.
2. QA: Added comment to user story confirming successful completion of test plan.