Fix/arboard clipboard context timeout

[fufesou]

This PR may fix #6859 on Linux platform.

Issue

arboard uses a fixed duration(10ms) as the timeout for x11 connection.

https://github.com/1Password/arboard/blob/77e0e078eb460ac2fa0eda96124163c11ef6b2d1/src/platform/linux/x11.rs#L142

But for RustDesk, sometimes it needs about 20ms or more to connect x11.

So the text clipboard is not stable.

And if the following line fails, the "copy & paste" from client to host will not work anymore in that connection.

rustdesk/src/client.rs

Line 726 in 7b31761

match ClipboardContext::new() {

Fixed

In this PR, retry and increasing timeout are added for new() and get_text().

        for i in 1..4 {
            arboard::Clipboard::set_x11_server_conn_timeout(dur * i);
            match arboard::Clipboard::new() {
                Ok(c) => return Ok(ClipboardContext(c)),
                Err(arboard::Error::X11ServerConnTimeout) => continue,
                Err(err) => return Err(err.into()),
            }
        }
        bail!("Failed to create clipboard context, timeout");

PR for arboard is also submitted.