Introduce visible annotations in variants

[orlinmalkja]

use visibleAnnotations to show the current visible annotations, instead of filteredAnnotations.

Filtered annotations should contain the annotations for the current visible tab.
Visible annotations should contain only the current visible annotations, i.e when switching the single select mode on, it should be empty. When we click at a target and i.e 4 annotations are shown in the list, then visible annotations should contain only these annotations.

[paulpestov]

Please add tests for switching between annotation tabs and the variant tab, also switching between different text panel tabs + variant tab. By introducing visibleAnnotations in the store, I cannot overview the consequences right now. I thought visibleAnnotations would be a local variable inside of VariantView where the changes to filteredAnnotations would have been bypassed to. But now it is a whole new state management.

[paulpestov]

I also see this when I open the arabic-karshuni page with the Dev endpoint (it's the first item in the first manifest):

[orlinmalkja]

@paulpestov regarding your screenshot above: The witness value for a certain annotation is null, therefore it brings an error while setting a color to the variant item.