Additional extensions based on real-world usage.

We've recently started working with the VideoLAN team to understand
more about media files they regularly encounter in the wild, which
may not have official IANA registrations.

In particular, here's the official list they support:
http://git.videolan.org/?p=vlc.git;a=blob_plain;f=include/vlc_interface.h;hb=HEAD

Some of these file formats are far too obscure to have official
MIME types at all, but for the ones that overlap with well-defined
standards, this CL registers those extensions as valid options.

-- Add SDP per https://tools.ietf.org/html/rfc4566
-- Add SMIL per https://en.wikipedia.org/wiki/Synchronized_Multimedia_Integration_Language
-- Add TTML per https://en.wikipedia.org/wiki/Timed_Text_Markup_Language
-- Add 3GA as a shortened version of https://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec
-- Add 3GP2 as shortened version of https://en.wikipedia.org/wiki/3GP_and_3G2
-- Add AC3/A52 per https://tools.ietf.org/html/rfc4184
-- Add M4B as audiobook version of https://en.wikipedia.org/wiki/MPEG-4_Part_14
-- Add M4P as protected version of https://en.wikipedia.org/wiki/MPEG-4_Part_14
-- Add several F4* variants per https://en.wikipedia.org/wiki/Flash_Video
-- Add ADTS per https://www.w3.org/2013/12/byte-stream-format-registry/mpeg-audio-byte-stream-format.html

-- Add MP4V/MPEG4 as alternative extensions
-- Add MP2/MP1/MPA as alternative extensions
-- Add MPEG2/MPV2/MP2V/M2V as alternative extensions
-- Add MPEG1/MPV1/MP1V/M1V as alternative extensions
-- Add M2T as tape-specific variant

Additional information available in RFC 4337.

Bug: 143549606
Test: atest --test-mapping frameworks/base/mime
Change-Id: Id24b6abbb5149ec8cdcb098f43ff611b01a69e96