Shift tenant to aggregateId part of streamId

[bartelink]

While the exact layout of a streamId is pretty arbitrary, in general it works better to have the tenant to the right of the '-' in the streamId as the default category projection treats anything to the left of the first '-' as the category (while this is configurable, this is the default, so Pit Of Success principles apply)

[bartelink]

(Not adding the following goldplated validation logic for now, (which I have implemented and used with success elsewhere) in the interest of not drowning the reader in trivia)

// Generates a stream id in the canonical `{category}-{aggregateId}` format
public static string ToStreamId(Type streamType, object aggregateId, object? tenantId = null)
{
    var tenantPrefix = tenantId == null ? $"{tenantId}_"  : "";

    if (tenantId != null)
        CheckNoEmbeddedDashes(nameof(tenantId), tenantId.ToString()!);
    var category = ToStreamPrefix(streamType);
    CheckNoEmbeddedDashes(nameof(streamType), category);

    // (Out-of-the box, the category projection treats anything before a `-` separator as the category name)
    // For this reason, we place the "{tenantId}_" bit (if present) on the right hand side of the '-'
    return $"{category}-{tenantPrefix}{aggregateId}";

    static void CheckNoEmbeddedDashes(string argName, string value)
    {
        if (value.IndexOf('-') != -1)
            throw new ArgumentException("Stream name components may not include embedded '-' characters.", argName);
    }
}

[oskardudycz]

Looks good, sorry for taking that long to approve it. Thank you for contribution!

Regarding validation, let's keep it simple for now :)