Evaluate allowing for stacking of codecs for encoding and decoding

[shiveshr]

Problem description
Currently service supports generating encoding id for a codec + schema pair.
If users wish to stack up multiple encodings, we may support ordered list of codecs + schema and generate an encoding id for it.
And corresponding encodingInfo would return the ordered list of codecs.
This would allow users to stack codecs while encoding the data and reference it with a unique id.

Pravega Serializers and deserializers would need to be updated to work with multiple codecs too.

Problem location
Encoding contract

Suggestions for an improvement
Allow for multiple codecs to be used for encoding the data.