Turn on line wrapping in usage and status messages, adds ANSI color to doctor and analysis messages. (#22656)

This turns on text wrapping for usage messages and status messages. When on a terminal, wraps to the width of the terminal. When writing to a non-terminal, wrap lines at a default column width (currently defined to be 100 chars). If --no-wrap is specified, then no wrapping occurs. If --wrap-column is specified, wraps to that column (if --wrap is on).

Adds ANSI color to the doctor and analysis output on terminals. This is in this PR with the wrapping, since wrapping needs to know how to count visible characters in the presence of ANSI sequences. (This is just one more step towards re-implementing all of Curses for Flutter. :-)) Will not print ANSI sequences when sent to a non-terminal, or of --no-color is specified.

Fixes ANSI color and bold sequences so that they can be combined (bold, colored text), and a small bug in indentation calculation for wrapping.

Since wrapping is now turned on, also removed many redundant '\n's in the code.