Move from mojo::DataPipe to mojo::CreateDataPipe in //mojo

The DataPipe constructor has no way to check for errors if creation
fails, so it CHECKs and crashes. CreateDataPipe offers a way to check
the return value.

This also adds two new CreateDataPipe() overloads: one that takes the
capacity_in_bytes as a convenience function for configuring the
data pipe's options, and another that uses references rather than
pointers for the out parameters.

Bug: 944990
Change-Id: Ie68e6c04019dabdff9ce6df2a682318f6958143f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2656415
Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#848139}