feat: add Spherical Video V1 UUID parsing support

[Diniboy1123]

Hey,

I wanted to insert metadata to VR optimized videos, but noticed that the Google official tool is Python2 only. So I decided to add support for the specific uuid box that the spherical video v1 spec requires to mp4ff to have a modern tool I can accomplish the same goal with.

I didn't implement v2 yet, because I didn't find a need for it.

Here is a test file from Google that parses just fine on my end with these changes now.

[Diniboy1123]

Would this be better off in its own function?

[tobbee]

@Diniboy1123 Thanks for the PR. Interesting format, but I'm a bit reluctant to add the XML parsing since it is not needed for the box parsing itself, and there is no inverse function to write a box from the parsed values, but just a simple encode of the raw XML: sw.WriteBytes([]byte(b.SphericalV1.XMLData)). Couldn't you just have an external program to parse the XML payload if needed and have the Info function just print the full XML?