Support ANSI code for clearing the rest of the line (ESC[0K)

Some programs use it to set the background color for the whole line.

  fzf --preview "printf 'normal \x1b[42mgreen\x1b[0K \x1b[43myellow\x1b[m\nnormal again'"

  fzf --preview 'delta <(echo foo) <(echo bar) < /dev/tty'

Fix #2249

src/tui/dummy.go

@@ -4,7 +4,7 @@
 
 package tui
 
-type Attr int
+type Attr int32
 
 func HasFullscreenRenderer() bool {
 	return false