[Editor] Use Icons for FindInFiles Buttons

[lodetrick]

This PR replaces the text in FindInFiles with icons and a short tooltip. This bring the FindInFiles more in line with the rest of the editor docks that use icons for these methods.

This PR Specifically changes the buttons in the top right:

Before	After

[arkology]

Can not test from commit artifacts (GH actions are stuck), but code and changes overall (I suggested them in #104676 (comment)) LGTM.

[KoBeWi]

This bring the FindInFiles more in line with the rest of the editor docks that use icons for these methods.

Theme editor does not use icons.

I'm not sure about this change. The buttons are not prominent enough and somewhat blend with the text next to them, making them potentially easy to miss. Also the closing X is next to the other X buttons, which have completely different function; it can be confusing.

[AThousandShips]

I think this hurts usability, also what other docs are you referring to? The only dock I can find that has a button for closing uses "Close"

[arkology]

Theme editor does not use icons.

BTW I have a branch with such changes. For ThemeEditor I think it suits better.