Problem: no support for terminal primary device attributes
Solution: Add support for detecting the DA1 response from the terminal,
add the v:termda1 variable and the 't_Ms' option for the
OSC 52 command format (Foxe Chen)
closes: #18033
Signed-off-by: Foxe Chen <chen.foxe@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>