whenever protoLoader handles a file import it will attempt to unify that file
into the overall 'package definition' for that package. However, since we were
invoking protoLoader multiple times we could end up failing to fully unify
some of those packages. Take for example:

  - file A imports file 'common/first.proto' in the 'common' package
  - file B imports file 'common/second.proto' in the 'common' package

if we load files A & B in separate protoLoader.load() calls then it cannot unify
them and each definition will have a partial view of the 'common' package. This
will cause issues when we attempt to lookup info on the 'common' package later.

loading all of these files at once will allow protoLoader to have a single view
of that 'common' package