Publish endpoint

[olenagerasimova]

Let's implement publish endpoint, the format is:

Endpoint: /api/v1/crates/new
Method: PUT
Authorization: Included

The body:
32-bit unsigned little-endian integer of the length of JSON data.
Metadata of the package as a JSON object.
32-bit unsigned little-endian integer of the length of the .crate file.
The .crate file.

For more details check the docs.