Before sending calling the `HandleClipboardData` member function on
the `PasteFromClipboardEventArgs` object when we receive a request
from the `TermControl` to send it the clipboard's text content, we
now display a warning to let the user choose whether to continue or
not if the text is larger than 5 KiB or contains the _new line_
character, which can be a security issue if the user is pasting the
text in a shell.
These warnings can be disabled with the `largePasteWarning` and
`multiLinePasteWarning` global settings respectively.
Closes#2349
985f85ddca