RFE: add a `--conflicts` flag to `port info`

[cooljeanius (Eric Gallager)]

port help info lists the following flags available for port info:

--category --categories --depends_fetch --depends_extract --depends_build --depends_lib --depends_run --depends --description --epoch --fullname --heading --homepage --index --license --line
            --long_description --maintainer --maintainers --name --platform --platforms --portdir --pretty --replaced_by --revision --subports --variant --variants --version

This covers most of the fields normally displayed by port info, however, it doesn't look like there's one for the conflicts field. It'd be useful to have a --conflicts flag for port info to make it easier to use in scripts in which one might want to know what ports a given port conflicts with. It could also have the command port conflicts as an alias or something.

(I think I might have brought this up in irc before, but I forget if it was this or something else...)

[kurthindenburg (Kurt Hindenburg)]

This was added in 2015