Improve translation mapping for enum like types

We currently do not have a consistent way to handle translation of things like enums. These usually come from the database as strings and need to be mapped to a human readable word.

One way we currently deal with this is by defining constant objects that can be used throughout the application. When we want to use them in a component we either have to add those as a public attribute or add them to the view model as <field>Verbose.
https://github.com/OpenSlides/openslides-client/blob/b5da8307ad7f9075a383c73b2a3bfe5d059576f1/client/src/app/site/pages/meetings/pages/polls/view-models/view-poll.ts#L76

Neither of those options is ideal as this always requires searching for those types and potentially overseeing them. Also both ways are quite verbose.

To improve the situation a central file that contains keyed translations should be created.
This file should contain key value pairs of enums/models and everything else that should be mapped from database strings.

This should be implemented with the missing translation handler. Keyed translations should get a prefix like ..

#5534 will implement this. This issue is for documentation and to keep track of adoption.