md files can't be edited

[jakobroehrl]

A tip on an office file opens the nextcloud files app for edit.
A tip on a md file just shows it. There is no possibility to edit it.
Proposal: Add an option to open this file in the nextcloud files app for edit.

[jakobroehrl]

@nickvergessen
Do we want to align the show/edit attachment function in iOS and Andorid?
nextcloud/talk-ios#676

[jakobroehrl]

This is still an issue.

[AndyScherzinger]

The bottom sheet menu on long press already exists since a while, so the ticket could be seen as resolved. #5898 however would extend the viewer implementation to also have a menu item to trigger opening it in the files app from there, not just from the chat message's menu.