This is both more accurate and works for rsync based transfers, where we
dont know the total size to transmit because of the streaming nature of
the rsync protocol.
The ForwardKeyEvent ibus signal is used to maintain ordering between CommitText events and non-IME key events.
The ordering is important for Korean IMEs, where it automatically commits text whenever a character is fully composed. This is different from Chinese/Japanese IMEs, where user manually presses a key to commit each word.
Without this patch, kitty can't handle non-IME key events when used with ibus-hangul, which utilizes ForwardKeyEvent signal.
Without ForwardKeyEvent:
```
key | sequence of events from application's view
r | UpdatePreeditText 'ㄱ'
k | UpdatePreeditText '가'
1 | (receives the reply to ProcessKeyEvent call: "native_key: 0x31 release: 0 handled: 0")
| -> UpdatePreeditText ''
| -> CommitText '가'
```
Application receives "1가", which is incorrect.
With ForwardKeyEvent:
```
key | sequence of events from application's view
r | UpdatePreeditText 'ㄱ'
k | UpdatePreeditText '가'
1 | (receives the reply to ProcessKeyEvent call: "native_key: 0x31 release: 0 handled: 1", and kitty discards the event)
| -> UpdatePreeditText ''
| -> CommitText '가'
| -> ForwardKeyEvent keysym=0x31("1")
```
Application receives "가1", which is correct.
Relevant ibus-hangul github issue to implement ForwardKeyEvent: https://github.com/libhangul/ibus-hangul/issues/42
Relevant changes in Qt to handle ForwardKeyEvent: https://codereview.qt-project.org/c/qt/qtbase/+/212179, https://codereview.qt-project.org/c/qt/qtbase/+/255587
