Prerelease v6.4.0-gimli.3

Summary

Adds a little more information to the handshake - and clients should now send over attempts and time spent doing handshake so we can use that for monitoring and metrics in the platform. Also got rid of the idea of using an enum for the sdkIdentifier - as that would require us to update contracts for every SDK we (or others) make, which isn't really a good idea. The sdkIdentifier is merely there for debugging purposes, kind of like the browser user-agent string.

Added

• More information to the handshake response
• Handshake attempts and time to the request

Changed

• Ordering of the handshake fields
• Name of the field sdk to sdkIdentifier