watch: Support simple 8 bit ansi escape sequences
See https://en.wikipedia.org/wiki/ANSI_escape_code#8-bit Support standard colors. The default ncurses colors ARE the first 8 of the 8-bit colors. This merge request only supports those. For the remainder, the behavior is unchanged.
The expected sequence is ";5;{n}"
Edited by Nipunn Koorapati