Rename create and delete commands to add and remove

[kirtangajjar]

currently to add and remove auth, we use following commands -

ee auth create example.com
ee auth delete example.com

compared to it, following feels much more intuitive -

ee auth add example.com         # adds auth on example.com
ee auth remove example.com      # removes auth on example.com

So I think we should be renaming it.

[kirtangajjar]

@danish17 Just ensure that the old commands also work for backward compatibility