refactor(tooltip): remove child scope

My stab at removing the child scope. This is a proof of concept right now. Opening this for discussion and review.

I considered replacing the directives with ngInclude since they're just placeholders for templates but I ran into issues removing the DOM as the ngInclude replaces the DOM node. Hence, I thought using ngInclude probably increases code complexity to handle its quirks. Anyways, using the popup directives might come in handy if we want some custom link logic.

Closes #1269 

Note: While working on this, I realized I introduced a watcher leak to the tooltip (similar to what was going on with the modals). Looking into that now. However, that leak is fixed here.