[Feature] Add branching logic to elements

[tertek]

Adding branching logic to Dashboard elements would improve the usability for many cases, e.g. only show Links/Buttons if a specific field is not empty.

How to achieve:

• Add "Branching" Button in Editor next to "Edit" Button that calls Branching Logic Modal. The Modal can be taken from REDCap Core or adopted. Validation necessary before save.
• Add calculation of Branching Logic during Render.