Flint: Prepare the UI to Mosca

This PR prepare Flint for the Mosca controller support.

It's a backport of !5647 (merged) into the up-to-date Flint architecture.

This can be merged without the BLISS mosca controller.

Closes #3927 (closed)

• Create dedicated concept of Mosca device
• Group statistics by device channel
• Collapse by default grouped statistics
• Plus various fixes

FYI @pguillou