Support ANSI OSC52 to copy content remotely

[aymanbagabas]

A wide range of desktop terminals now support ANSI OSC52 escape sequence to manipulate the clipboard. Adding support for this means the user can copy content remotely using the escape sequence.

[migueldeicaza]

This is a fine idea, let me research whether this is considered a security problem or not. I recall xterm put this behind some flag.

Some discussions:

• https://gitlab.gnome.org/GNOME/vte/-/issues/2495
• https://github.com/mintty/mintty/issues/258
• https://bugs.kde.org/show_bug.cgi?id=372116
• https://chromium.googlesource.com/apps/libapps/+/master/nassh/doc/FAQ.md#Is-OSC-52-aka-clipboard-operations_supported

Seems like writing to it is relatively safe, and perhaps a warning can be added

[migueldeicaza]

(Btw, SwiftTerm the library already supports this, this is a matter of wiring up the request copyClipboard, and determining what UI is necessary for it)

[migueldeicaza]

This has been implemented, and will be in the release after the next (1.0.11)