hterm: handle ctrl-v/ctr-shift-v pasting ourselves
hterm: handle ctrl-v/ctr-shift-v pasting ourselves

Since not all browsers/OS's binding Ctrl-V to paste (e.g. macOS only
binds Command+V), make our Ctrl-V handler do the pasting ourselves.
This way we get consistent behavior across all platforms.  If people
don't want Ctrl-V to paste, they can do their own keybinding:
	{
		"Ctrl-V": "PASS",
		"Ctrl-Shift-V": "PASS"
	}

BUG=chromium:737299

Change-Id: I1213575c0e481f86c6323a4f2c67a06a778085a0
Reviewed-on: https://chromium-review.googlesource.com/551275
Reviewed-by: Brandon Gilmore <adbfbaf7e4f927b45ce8ad3e5043a632414a833b@google.com>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>

chromium/hterm,chromium/hterm,chromium/hterm,chromium/hterm