Turn --authfile into an alias for --auth-file

[mtrmac]

Feature request description

As discussed in containers/common#1731 , we will have login --authfile vs. login --compat-auth-file; it would be better to be consistent everywhere; and --authfile unnecessarily concatenates words.

Suggest potential solution

In c/{common,buildah,podman,skopeo}: replace all existing --authfile options by an --auth-file spelling, and keep --authfile as an alias.

[Luap99]

I tend to prefer option names with words separated by - so this sounds fine in principle to me but I think @rhatdan is/was a strong opponent of them.

But in general my question would be what value a rename of such a widespread options adds, this certainly leads to some confusion on how the option is really named if you see both variants used in the wild. There are old docs, scripts, etc...
Given we are going to have to keep --authfile supported anyway I am not sure what value --auth-file actually adds here besides improving the name a tiny bit.

[rhatdan]

I don't like large named options mainly for the amount of typing. I know completions help this out some, but not for scripts. I believe for ease of use the shorter the option name the better. I really hate sentence names for options.

But I do like consistency, haveing --authfile and --compat-auth-file is not good. Making these consistent, is the goal. So go either way.

[rhatdan]

man ls
...
--dereference-command-line-symlink-to-dir

Yuck, as an example. Good luck typing that option correctly.