VideoPress: Insert v6 block for VideoPress videos on Gutenberg Inserter Media tab

[lhkowalski]

This is part of an idea to improve the VideoPress experience inside the new Media tab on the Gutenberg Inserter.

• when a VideoPress video is selected, a videopress/video block should be created
• currently, a core/video is inserted, what results on
  • different experiences for Jetpack plugin users vs. VideoPress standalone plugin users (v5 block vs. pure core video block)
  • the user not having access to the full functionalities of the VideoPress block

Notes:

• this feature depends on the Inserter Media tab becoming extensible. More info on pe4Cmx-LC-p2.

This issue is related to #28651.