Support binary uploads to entity-service

[hardbyte]

An experimental api has been added for uploading CLKs as a binary file. This is to allow for faster and more efficient data transfer. The same rest endpoint (/projects/{project_id}/clks) is used.

Additional headers are required:

Content-Type: application/octet-stream
Hash-Count: XX
Hash-Size: YY

The uploaded stream is simply a packed serialization of (index, CLK data, popcount):

bit_packing_fmt = "!1I<Hash-Size>s1H"

Where:

• "!" Use network byte order (big-endian).
• "1I" Store the index in 4 bytes as an unsigned int.
• <Hash-Size>s the length of a hash in Bytes. Default value is "128s". Store the 128 raw bytes of the bitarray.
• "1H" The popcount stored in 2 bytes (unsigned short)

https://docs.python.org/3/library/struct.html#format-strings

Aha! Link: https://csiro.aha.io/features/ANONLINK-26