repo-add: reorganize output messages for clarity

repo-add: reorganize output messages for clarity

The use of warning once we had already started adding a package was
confusing as it broke the standard indent pattern. It was especially bad
if adding multiple packages as it wasn't clear what sub-messages applied
to which package being added. This should be an output change only from:

    ==> Adding package '/tmp/sync/netcfg-2.6.7-1-any.pkg.tar.xz'
      -> Computing checksums...
      -> Adding package signature...
    ==> WARNING: An entry for 'netcfg-2.6.7-1' already existed
      -> Removing existing entry 'netcfg-2.6.7-1'...
      -> Creating 'desc' db entry...
      -> Creating 'depends' db entry...

to:

    ==> Adding package '/tmp/sync/netcfg-2.6.7-1-any.pkg.tar.xz'
    ==> WARNING: An entry for 'netcfg-2.6.7-1' already existed
      -> Computing checksums...
      -> Adding package signature...
      -> Removing existing entry 'netcfg-2.6.7-1'...
      -> Creating 'desc' db entry...
      -> Creating 'depends' db entry...

Signed-off-by: Dan McGee <dan@archlinux.org>