Add colours to argparse interpolated values in `--help`

[alexprengere]

Feature or enhancement

Proposal:

#141680 was merged, but only applies when argparse.ArgumentDefaultsHelpFormatter is used.
I suggest to apply a similar change for all interpolated values, like when the help text leverages %(default)s to show default value(s):

Excluding tests, the change is fairly simple, it is a 4 line change in argparse _expand_help method.

I am not sure if this should apply to just default or other interpolated values like choices.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-141939: Add colors to interpolated values in argparse #141940