Draft: findrep: Enter should only activate Find/Jump if pane focused

Some commits which landed in 45.0 improve quality-of-life in the find/replace/jump dialogs to the extent that 'Enter' will now activate the default action. However, it's a bit janky in the sense that Enter will still work to activate the default action if the main hex editor widget has the focus. So this draft MR changes that.

However, an unintended consequence is that it's really hard to see the cursor in the main hex view as we cycle through search results. That is simply a result of how the cursor is rendered when the widget is not in focus. So this needs some further design before it can be merged. Perhaps the reddish colour of the search highlighting could be changed to make it easier to see the dashed cursor? Perhaps the cursor should blink when in "cycling-through-search-results" mode? I'm not sure but I'm open to suggestions 😄