Enhancement: Allow drag and drop of video to replace VideoPress block

### Impacted plugin

Jetpack

### What

If you drag in a new video file to the block editor, you should be able to drop it on top of an existing video block to replace the block with the content of the new video.

### How

The image block supports this if we need inspiration on how the UX works.

Start by locating the Jetpack VideoPress block implementation and comparing its drag-and-drop behavior with the image block, which the issue identifies as the UX reference. Done means dropping a new video onto an existing VideoPress block replaces that block with the new video content and preserves the expected block-editor behavior.

Written by the indexing model from the issue text.