feat: add app-specific line break handling for o and +o in insert mode

[rcmdnk]

Some applications, such as ChatGPT, use Enter to send a message and require Shift+Enter or Ctrl+Enter to insert a line break.

In Normal mode, vim_ahk currently sends Enter when executing o or O. In these applications, this may send the current message instead of opening a new line.

This PR adds the VimShiftEnter and VimCtrlEnter application groups and uses the appropriate key combination when handling o and O.

For now, these groups are hard-coded, so users need to edit the vim_ahk script directly to add or change applications.

Current list:

    ; Shift-Enter to insert line break in these applications
    GroupAdd("VimShiftEnter", "ahk_exe ChatGPT.exe") ;
    GroupAdd("VimShiftEnter", "ahk_exe Claude.exe") ;
    GroupAdd("VimShiftEnter", "ahk_exe Cursor.exe") ;
    GroupAdd("VimShiftEnter", "ahk_exe slack.exe") ;
    GroupAdd("VimShiftEnter", "ahk_exe ms-teams.exe") ;
    GroupAdd("VimShiftEnter", "ahk_exe Teams.exe") ; Old version
    GroupAdd("VimShiftEnter", "ahk_exe Discord.exe") ;
    GroupAdd("VimShiftEnter", "ahk_exe WhatsApp.exe") ;
    GroupAdd("VimShiftEnter", "ahk_exe Zoom.exe") ;
    GroupAdd("VimShiftEnter", "ahk_exe PhoneExperienceHost.exe") ;
    GroupAdd("VimShiftEnter", "ahk_exe LINE.exe") ;

    ; Control-Enter to insert line break in these applications
    ; No corresponding applications

Making these groups configurable from the settings window would be useful. However, adding more application-specific options there would make the window increasingly complex, while several other settings also remain hard-coded. A separate configuration mechanism may eventually be needed to manage these settings (#129).

Partially addresses #128.