Implement Spherical video metadata V2 extraction in MKV/WebM

Implement Spherical video metadata V2 extraction in MKV/WebM

- No stereo-mode support added as far as it is stored using the
  existing StereoMode element specified in the Matroska spec. and
  can be supported in the Matroska format parser

- WebM files prepared with MKVMerge tool with "-w" option turned on
  (force WebM sub-format) are not recognized by libmm-fileinfo

- Ambisonic audio is not specified in Google's RFC v2

Change-Id: I4935602afb658bfa6971be247a4ffd1e3332fe55
Signed-off-by: Mykola Alieksieiev <m.alieksieie@samsung.com>