Make scripts editable in Fleet UI

[eugkuo]

Goal

User story
As an admin,
I want to be able to edit scripts within the Fleet UI
so that I can quickly fix typos or other errors without having to download and re-upload the script.

Key result

Original requests

• Add script editor in the UI #23767

Context

• Product designer: @eugkuo

Changes

Product

• UI changes: Figma | Prototype
• CLI (fleetctl) usage changes: TODO
• YAML changes: TODO
• REST API changes: TODO
• Fleet's agent (fleetd) changes: TODO
• Activity changes: TODO
• Permissions changes: TODO
• Changes to paid features or tiers: TODO
• Other reference documentation changes: TODO
• Once shipped, requester has been notified
• Once shipped, dogfooding issue has been filed

Engineering

• 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

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.

[eugkuo]

FYI @noahtalerman I've added this prototype to show editing scripts from the script library page.