patch 9.0.1834: Some problems with xxd coloring

patch 9.0.1834: Some problems with xxd coloring

Problem:  Some problems with xxd coloring
Solution: Fix the following problems:

* Support colored output on Windows.
  SetConsoleMode() is required to enable ANSI color sequences.
* Support "NO_COLOR" environment variable.
  If "NO_COLOR" is defined and not empty, colored output should be
  disabled.
  See https://no-color.org/
* "-R" should only accept "always", "never" or "auto" as the parameter.
* Adjust help and documentation. "-R" cannot omit the parameter. Remove
  surrounding brackets.

Related #12131
closes: #12997
closes: #12991
closes: #12986

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: K.Takata <kentkt@csc.jp>