[Feature] [Breakdown] Add quicker/one-step way to assign an existing element to selected text

[hyuri]

Issue

Right now, the only way I found of adding an existing element to a selected piece of text is by clicking on "add element" then renaming it to get the element you want show up in the search, clicking on it and finally clicking on "create".

But we are not really creating a new element, so it's confusing, and there should be a quicker way to simply associate an existing element with the selected text.

I found the option "Add existing element" in the "Additional options", but it doesn't seem to do anything.

Proposal

Two ideas come to my mind. And both would be helpful and could be implemented, they are not mutually-exclusive:

1. In both the left and right Elements panels, in the element context menu, add the option "Add to Selected". This adds the element to the selected text;
2. In the context menu for the selected text itself, add the option "Add Existing Element", which would bring up a search field where you can type the name of the element, select it and click OK to confirm.

I think both would be very useful to have.