Allow provider admin pages to expose editable settings in the shared settings form

Problem/Motivation

The shared provider admin form in video_style currently assumes that provider pages are informational only. That becomes limiting as soon as a provider module needs to expose real Drupal-managed settings on its admin page.

A current example is video_style_imagekit, which now needs a configurable upload method. The base form should support editable provider settings in a Drupal-native way instead of forcing provider modules to work around the shared UI structure.

While making that change, the provider admin page layout should also be tightened so that actionable configuration comes first, followed by operational diagnostics.

Steps to reproduce

1. Install video_style and a provider module that needs editable provider-specific settings on its admin page.
2. Open the provider settings page under /admin/config/media/video-styles/....
3. Observe that the shared base form is structured around status and setup output, but does not provide a clean shared pattern for editable provider settings and in-section save actions.

Proposed resolution

Update the shared provider settings form in video_style so that provider modules can expose editable settings through a dedicated Settings details element.

The shared form should:

• support provider-defined editable settings elements,
• allow the save action to live inside the Settings section when the page contains editable settings,
• keep provider-specific implementation details in the provider module, and
• present the remaining operational sections in a cleaner order.

The updated provider page structure should be:

1. Settings
2. Sync health
3. Runtime status
4. Setup snippet

Both Sync health and Runtime status should be collapsed by default.

Remaining tasks

• Update the shared provider settings form in video_style.
• Verify that provider modules can add editable settings without custom page-level form workarounds.
• Confirm that the updated section ordering and default collapsed states work correctly.
• Update any relevant maintainer-facing documentation if needed.

User interface changes

Yes.

Provider admin pages can now expose editable settings in a first-class Settings section, with the save action placed inside that section. The operational sections are reordered so that Sync health appears before Runtime status, and both are collapsed by default.

API changes

Yes, in the shared base form layer.

The shared provider settings form gains extension points for provider modules to define editable settings elements and, where needed, customize the settings submit action label.

Data model changes

No.

This issue changes shared admin form infrastructure only. Any provider-specific persisted configuration remains the responsibility of the provider module.