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

Feature request description

As discussed in https://github.com/containers/common/pull/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.