fix(help)!: Consoldiate color settings

[epage]

A lot of users expected color feature flag and ColorAuto etc to
control all colors. Having this extra flag around is easy to miss and
adds to our overall settings bloat, making it harder to find settings
people want.

This completely removes it, rather than make it deprecated like
functions in #2617, because there is extra work to mark things
deprecated as Settings and we should decide on our strategy first before
investing time in addressing that issue.

Fixes #2806

[pksunkara]

bors r+

[bors]

Build succeeded:

• CI

[dbrgn]

Hi, I was surprised by this change. I'm exactly the person mentioned by @pksunkara in #2055 that wants colors in error messages, but not in help pages. That's why I enabled the colors feature, but did not opt in to the ColoredHelp feature.

I'm the maintainer for tealdeer and am currently porting the codebase to clap v3. When the colors were enabled by default during the update from beta 4 to beta 5 we discussed whether we should keep the help colors or not. Reasons why we decided against it:

• I'm not really sure if colored help texts are an improvement in readability, or just a distraction. I myself am not a big fan of them for that reason.
• Whether it looks good or not depends on the terminal settings. It might look good on some terminals, while it might look bad on others. (I know that this is a "the user can fix the colors" kind of thing, but some terminals only support very few colors, and this whole topic is something that users previously did not need to care about.)
• As a user, I can disable help colors by setting NO_COLOR=1, but this will disable all colors, which may not be intended.
• The tealdeer CLI program outputs colored content. This output can be styled through the config file. If the help text now contains colors as well, users will want to configure those colors. This results in feature requests for tealdeer (I wouldn't want to implement such a feature) and it would also result in a feature request for clap (right now colors aren't configurable, right?).

In contrast to the help texts, I think that colored error messages do improve the user experience. However, if there's no way to turn off colored help texts, I'll turn off colored error messages as well.

Please reconsider.

[pksunkara]

DisableColoredHelp setting can be added if @epage agrees.

[epage]

I've split this conversation out in #2906 so we don't lose it in the comments of a PR and have a little more flexibility in how to handle it.