[BUG]: Confusing label "Add" and pickers that keep state

[enkelmedia]

This is not a "bug" but maybe more of a communication thing.

I've noticed that many of the pickers (Content Picker, Multi Node Tree Picker, Template Picker and more) will populate the selected state when the modal is opened.

Notice here that when I click "Add" for the 2nd time the two selected nodes are active in the tree and I can un-select them to remove them from the content picker.

I guess that this might be a good thing in some scenarios, but I also think that in many scenarios we should:

• Change the label of the dashed picker button to "~~Manage~~", "Choose" or ~~something~~
• ~~Keep the label but not pre-populate the state.~~

Also: Update the "Submit"-text in the modal to something more contextual.

Progress:

• [ ] Content Picker
• [ ] Multi Node Tree Picker
• [ ] Template Picker
• [ ] ....