feat(runtime): implement ParachainHost_para_backing_state runtime call

[EclesioMeloJunior]

Changes

This PR introduces a new runtime call function ParachainHost_para_backing_state which retrieves informations about the current backing state for a single parachain, these informations contains the current Constraints, which are used by Prospective Parachains to validate incoming candidates, also PendingAvailabilityCandidates which are candidates backed on-chain that is waiting the availability step, they are also used by Prospective Parachains in order to select possible next candidates.

• Added to parachaintypes:

  • Constraints
  • BackingState
  • CandidateDescriptorV2

• Used the most up to date runtime available

• Changed wazero/Instance to not hold an instance of the runtime, that is not needed once we bootstrap the runtime from a cached compiled module, also this field was not being used.

Tests

 go test -timeout 10m -run ^TestInstance_ParachainHostParaBackingState$ github.com/ChainSafe/gossamer/lib/runtime/wazero

Issues

• Closes Implement ParachainHost_para_backing_state runtime call #4416

[haikoschol]

just some nits, good to merge as is

[jimjbrettj]

Could we give better naming/descriptions to the two differed reserved bytes fields here?

[EclesioMeloJunior]

in the RFC they call them as reserved, that's because they want to be compatible with the V1 as they changed some fields, but in their code they just used reserved and does not have future plans for them

[jimjbrettj]

lgtm, just some minor feedback