Add Support for Mongo Update Operators as Patch

[satabin]

See: https://www.mongodb.com/docs/manual/reference/operator/update/#std-label-update-operators

Another patch format would be interesting to generate diffs that are compatible with mongo update operators. Patches have some limitations here, as several operations on the same array are not supported in all cases. The algorithm for this would be somewhere in-between LCS based and simple diffs as implemented for JsonPatch