File Compare: use standard macOS search functions and accelerators

Currently, SmartGit (and your other tools) use non-standard search functions on macOS:

- Command-E does nothing

- Command-F changes the search string to whatever is selected

- The search text isn't shared with other applications, and is inconsistent, e.g.:

    1) Open Find, enter some common text (call it "A"), and search successfully

    2) Close the Wind window

    3) Make sure no text is selected and then open Find again: you'll see the same text you searched for before

    4) Enter some garbage text (call it "B") and Find; dismiss the "Didn't find" warning and close "Find"

    5) Use Command-G: it'll find the previous text ("A")

    6) Make sure no text is selected and then open Find again: you'll see the garbage text ("B")

It should use the standard search functions described in Apple's UI standards:

https://developer.apple.com/design/human-interface-guidelines/macos/user-interaction/keyboard/

- Command-E should set the shared search string to the currently selected text

- Command-F should open, showing the shared search string

- Changes to the search string should be shared with other applications

- Command-G should search with the shared search string; if it can't be found, then alarm (don't open a dialog)

- Have an option to allow wrap-around searches without prompting dialog