* remove v0 primitives from polkadot-primitives
* first pass: remove v0
* fix fallout in erasure-coding
* remove v1 primitives, consolidate to v2
* the great import update
* update runtime_api_impl_v1 to v2 as well
* guide: add `Version` request for runtime API
* add version query to runtime API
* reintroduce OldV1SessionInfo in a limited way