(feat) Deprecation of frontend/backend images

[enchant97]

Proposal

1. No longer build separate frontend and backend images (and eventually remove them from package list)
2. Rename note-mark-aio to just note-mark

Why

Running two containers for the frontend and backend adds no value and can make the setup more complex than needed. Since Note Mark now has a sucessful all-in-one image, it now makes sense to only use this.

Migration

Replace both frontend and backend containers with the all-in-one image.

Timeframe

Not in a hurry, it will effect people's working setups. This issue gives people the warning that they should migrate in preparation.