Revert "Revert "[clang-format] Keep protobuf "package" statement on one line""
Top-level "package" and "import" statements should generally be kept on
one line, for all languages.
Reviewers: krasimir, sammccall, MyDeveloperDay, xinz, dchai, klimek
Reviewed By: krasimir, xinz, dchai
Differential Revision: https://reviews.llvm.org/D60661