Snowflake - Add Producer Constructor

[TheBrambleShark]

Description
This change should add a constructor to the Snowflake type intended for use by servers, or more accurately, producers of new Snowflake values.

API Proposal

public Snowflake(DateTimeOffset timeStamp, byte internalWorkerId, byte internalProcessId, ushort increment, ulong epoch = 0);
public Snowflake(DateTimeOffset timeStamp, byte internalWorkerId, byte internalProcessId, ushort increment, DateTimeOffset? epoch = null);

These methods likely would not be able to forward to the existing Snowflake(ulong, ulong) ctor due to the need for a method body to perform multiple mathematical operations.

Why This is Needed
Currently, the Snowflake type is intended for use solely by consumers, e.g. those who are sent Snowflake values over an API or who store them in a database. This is not suitable for producers of this type, who would currently need to produce the Snowflake value themselves as a ulong, then pass that to the Snowflake(ulong, ulong) ctor.

[TheBrambleShark]

Example Use:

ushort increment = 0;
public User CreateUser(string emailAddress, string firstName, string lastName)
{
    var userId = new Snowflake(DateTimeOffset.UtcNow(), _context.WorkerId; System.Environment.CurrentManagedThreadId, increment++, Constants.MyServiceEpoch);
    
    var user = new User(userId, emailAddress, firstName, lastName);
    
    // Todo: write user to database
    return user;
}