* size computations
* add `Protobuf.computeSize` to compute the encoded size of an object
* readd `VarIntLengthPrefix` support
* don't expose loosely typed `writeValue` for objects that might
conflict with other serializers
* ensure all `writeValue` and `writeField` are tagged with a `codec`
type
* avoid writing all-defaults proto3 object fields
* Fix sizer for reference
* Create TableObject in a template
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Co-authored-by: Ludovic Chenut <ludovic@status.im>
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