add TypedRecord and TypedRecordRef

[bluejekyll]

@djc, here are the types I was suggesting. It's possible that TypedRecordRef is not necessary if we deprecate Record and replace all use cases with TypedRecord. A different option instead of deprecating would be to do a type alias of type Record = TypedRecord<RData>. I'm not sure which would be better for downstream dependencies.

If you like this, I can add everything necessary to make all RecordData be compatible with this, currently only SOA implements RecordData.