Change background on hover for debug control buttons

[reberhardt7]

There are two sets of debugger controls: the controls in the Processes tab, and the inline controls:

When you mouse over a button in these controls, the cursor changes to the glove to indicate it's a button, but that's the only indication that those things are clickable. It may help the usability of the UI to also make the button background change on hover. (We do that for basically every other clickable element in cplayground right now.)

[NoahGeller]

Working on this!