Url label format

[spalger]

Fixes: #3747

Adds a template to Url formatters that allows customizing the content of the link tag.

[lukasolson]

This looks good. My only feedback would be to provide an example in the help boxes of how to use the double curly brackets to utilize value or rawValue. But meh. If you want someone else to take a look, feel free to assign it. Otherwise, go ahead and merge.

[spalger]

Added some help text. What do you think?

[pagenbag]

Can we please have an option to exclude the target="_blank" on the links ? Or to be able to specify it.
When using the dashboards or visualizations in shared/embeded in an iframe - it makes sense to be able to redirect the page/iframe instead of opening a new tab each time.