Fixed #9531 - highlight search box when filled, add clear button

[snipe]

This PR looks noisier than it seems, just because I generated new skins with a new .search-highlight class, in case we wanted to change the colors of the highlight per skin.

Basically it just adds a new searchboxHighlighter() method to the javascript that checks for a value in the search box and highlights it if there is a value, and also adds an X to clear the box. I'd personally prefer an inline X (like we have in the Super Admin Settings search, but Bootstrap Tables kind of doesn't want you to do it that way, they want it as an input group.

This fixes #9531

[uberbrady]

I think this is going to be really nice addition - I can't tell you how many times I'm helping with a customer's instance and I get confused because I forgot I typed something, then I can't see stuff. Happens to me on the AWS console all the time.

Very approved, with very slight whining about the unrelated changes that are inappropriately munged into this PR. Shame shame. But keep signing my paychecks and I'll let it slide :)

[snipe]

Everyone's a critic ;)

[MWR-Napavine]

I just noticed that you implemented the feature. Thank you kindly!