Evaluate to refactor all classes

[mfranzke]

Either replace or prepend all existing namespaces of elm-/cmp-/rea- (and possible future tpl- for templates, all of which inform the users of their types) by another namespace (e.g. db-).

[d-koppenhagen]

I would really love to see only the prefix / namespace db- instead of all the different ones we have by now.
The reason: it makes it way more recognizable as developers must only remember the db- namespace.
As a consumer of DB UI Core it's not important for me to reflect the category of the element in the namespace. I want to use elements easily without thinking about what type of element I am using.

Probably there could be a transition phase where already the new namespaces are available but the old ones are still supported to migrate smoothly step-by-step. Otherwise the Breaking Change should be documented well with detailed migration instructions (or even a script / regex for helping to search/replace)