Expandable advanced search UI panel

[cpradio]

@codinghorror

One minor tweak. When filling in the user and populating the search field, don’t use

user:username

but instead

@username

This is done. I also updated the qunit tests so they stopped failing due to the removed markup from

Advanced Search UI

Just a note, I find “in Group” and “with Badge” to be so hyper-specialized I’ve commented them out in the HTML markup for now.

https://github.com/discourse/discourse/pull/4489