Find in Files Improvements (Part 1: Templates)

As I mentioned in #3151 I am going to simplify the review and test tasks by splitting the pull request into smaller steps.

For this first part I just changed the jQuery html creation with Mustache templates for the search dialog and results, and added a row selection like JSLint uses. There might be a problem with the selection color since the highlighted query and the selected row use the same color, but since the search query is also selected in the document, this might not be that big of an issue. If it is, we could change the color for one of them, or use a different color for the highlighted query when a row is selected.