Fix text-input Chinese input

[qingyiwebt]

Now IME is allowed for the window winit created, and the text input can handle the ImeCommit event,
BUT the render issue when there is CJK text in the text-input still exists.

[qingyiwebt]

QQ2025430-231030-HD.mp4

[dzhou121]

We probably should call set_ime_allowed(true) when text input is in focus, and set_ime_allowed(false) when it's out of focus.

https://github.com/lapce/floem/blob/main/src/action.rs#L213

And call set_ime_cursor_area to put the IME candidate box.

[qingyiwebt]

Ok, I will try to solve it tomorrow.

[qingyiwebt]

The calling of set_ime_cursor_area and some fixes is also added in the commit enable IME when text-input focused

[qingyiwebt]

Now text-input should work better with CJK characters and IME, the text overflow problem and cursor position should be fixed too.

QQ202551-125246-HD.mp4

[dzhou121]

There could be issue when the focus is switched from one text input to another, and we can't guarantee the execution order of the set_ime_allowed, so when the loosing focus text input execute this later than the gaining focus one, the ime would be disallowed. We need a central state of whether ime should be allowed.