`Escape` key reopens the closed searchbar, and can be called from anywhere in the main window

[nekohayo]

This is a very minor bug I have found in the git master version today, related to #1003 and #952. It seems that #1106 (or something else afterwards) introduced a slight oversight where you can reopen the searchbar by pressing the Esc key.

To reproduce:

1. Ctrl+F
2. Press Esc to dismiss the searchbar
3. Either press Esc immediately, or select something else in the main window (ex: click in the quick-add entry) and press Esc

Result: the searchbar reopens (essentially, Esc acts as a toggle). That's not really a normal/expected behavior, I've never seen that in other applications. When the searchbar is not focused, the Esc key would normally be used to cancel or defocus whatever else is focused (if applicable), so it's probably best if the searchbar doesn't interfere with that shortcut when it doesn't have focus.