Add Edit input button to the Input Diagnosis page

[ousmaneo]

Editing an input was only reachable via the "Edit input" item buried in
each row's More menu on the inputs overview. Clicking an input name opens
the Input Diagnosis page, which had no edit affordance, making a basic
action hard to discover.

Add an "Edit input" button next to the diagnosis tab control that opens
the existing edit modal. The action reuses the existing InputForm modal,
the updateInput mutation, telemetry events, and the same permission gate
(inputs:edit + input_types:create) as the overview row action.

/nocl
fix #25430

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have requested a documentation update.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.

[gally47]

Looking good, but the Input Diagnosis page is not picking up the input updates like Title edit.

[gally47]

LGTM.