Support for subject verification

**Is your feature request related to a problem? Please describe.**
So, as I understand in `CompreFace` we have only two options for face verification: using `embeddingId` or providing two images to compare.
But if we have many photos of the same user (`embeddings` which are associated with the same `subjectName`), can't we improve the verification results?
We can, for example, use `subjectName` for verification and calculate distances between `input-embedding` and several stored `embeddings` to avoid more then one round trip to the `compreface-api` server.

**Describe the solution you'd like**
Provide API for `subject-verification`

**Describe alternatives you've considered**
-

**Additional context**
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