Option to force ANSI color codes or disable TTY detection

[gdewald]

ANSI Colors are automatically disabled in some cases, I would like to request some option to disable this feature for cases where the output may be captured outside of a TTY but color codes are still desired.

Specific use case: GitLab CI supports color codes in output, however Click applications don't appear to output color codes when executed in this context.

[davidism]

Essentially duplicate of #2207, but with the bool flipped.