Make the shortcuts in SIA customizable

[0loid]

Is your feature request related to a problem? Please describe.
Different users have different preferences. Some of our annotators reported the wish to have the keyboard shortcuts customizable.

Describe the solution you'd like
As this is user dependend it should be, if implemented, be a user specific configuration

Describe alternatives you've considered
If a user group for an annotation task could agree on a central configuration. It might be an option to have the shortcuts configured during the pipeline design by a configuration file.