The python3 fallback for `make_encoded_file()` produces different results on py2 and py3 when bytes are passed. This CL makes it clear breaking it into two methods, one for text and another for bytes. This CL also adds a fallback in `download_file` for py3 to return bytes when it cannot decode the downloaded file into utf-8.

Recipe-Manual-Change: chromiumos
Change-Id: I3d313e430c852e179825bc24bf4a58ce84440b2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3595026Reviewed-by: Gavin Mak <gavinmak@google.com>
Reviewed-by: Greg Edelston <gredelston@google.com>
Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>