orchestrator: Generate MPEG7 perceptual hashes for fast verification

[jailuthra]

What does this pull request do? Explain your changes. (required)

Add capability to generate mpeg7 perceptual hashes on the transcoder node, and send them back to the broadcaster with the renditions.

Specific updates (required)

• 9c4cc8b - a34b3cd Already reviewed in net,core: add fields for signatures in B<>O messages #2006 and orchestrator/transcoder: calculate perceptual signatures and upload to OS #2007
• d3a79a4 Os returns Capability_MPEG7VideoSignature in the capability bitstring, so that Bs on the network know which O supports the new capability
• ca7fc31 For split O-T setups, send the generated perceptual hashes from T to O in the multipart return, interleaved with the segments.

How did you test each of these updates (required)

Locally tested that perceptual hashes are being generated in both combined and split O-T setups, if the B asks for it by setting md.CalcPerceptualHash = true. Also tested that the URI communicated from O to B for downloading the pHash works.

Does this pull request close any open issues?

Fixes #2035

Checklist:

• Read the contribution guide
• make runs successfully
• All tests in ./test.sh pass
• README and other documentation updated
• Pending changelog updated

[darkdarkdragon]

LGTM

[yondonfu]

LGTM after squashing