Namespace-scoped Marker DELETEALL action

[hidmic]

Feature request

Feature description

Current Marker and MarkerArray displays support DELETE actions, to drop markers one by one based on their ID, and DELETEALL actions, to all markers associated with that display. However, having a third delete variant, a namespace-scoped DELETEALL action, would greatly simplify applications that use many markers and namespace them based on some application-specific logic or concept to simplify the interaction (i.e. through visibility checkboxes).

Implementation considerations

This is an easy and ABI-compatible feature addition. All delete logic would be restricted to this switch case.