Reset to default button for plugin settings.

### Feature Description

Settings from the shell itself who have default value can be reset with this button

But this button isn't available for plugins settings even tho it is possible for them to have a default value.
The feature request is simple making this button available for plugins settings when the setting have a default value defined.

### Use Case

Well to reset the setting to its default value.

### Compositor(s)

All compositors

### If Other, please specify

_No response_

### Proposed Solution

_No response_

### Alternatives/Existing Solutions

_No response_

Start by locating the existing reset-to-default button for shell settings and the plugin settings UI, then compare how each setting exposes a default value. The work is done when plugin settings with defined defaults show the reset button and restore the default value across all compositors.

Written by the indexing model from the issue text.