This feeds into efforts to create a working install target.
The order of headers is still funky, and was "fixed" by clang-format,
but in a way that doesn't exactly align with the style guide. Further
cleanup of header order is coming in a follow-up PR.
This CL also removes EncryptionConfig stream data type and merges it
into StreamInfo/SegmentInfo instead.
Change-Id: Idb70ce503e61d3c951225cc78b6b15c084e16dcd