feat(lib/grandpa): verify GRANDPA justification before applying the block

[timwu20]

Changes

• Rework of feat(lib/grandpa): verify justification before applying the block #4084

Taken from #4084:

This PR promotes some changes on how Gossamer import a block while full sync
Currently, Gossamer first imports a block/apply the blocks' extrinsic against the state and then it will verify the justification that exists in the block. This PR wants to change that by moving the verification step to be the first in the importing process, then we avoid to import or modify the state with invalid informations (impacting the resiliency of the node)

Differently than I thought, these modifications will require more changes in how our current validation function performs the check, the main point is that the validation rely on the state to check ancestry and also that our current Justification struct miss one field called Ancestors.
That is done by bringing the changes from the feature branch feat/grandpa given that the branch already contains the changes needed to verify the justification correctly.
The main drawback is that it brings a lot of changes from the feature branch, however I tried to reduce the amount of components bring only the required ones for the justification validation

Tests

go test -tags integration github.com/ChainSafe/gossamer

Issues

close #3468

[jimjbrettj]

Couple small comments, but overall lgtm

[dimartiro]

LGTM, just a few nits and some questions