Optimally use snapshot structure in bor consensus

[manav2401]

Rationale

I believe there's lot of duplicate work being done in bor consensus. The snapshot structure in bor caches a lot of things yet we fetch them from contract multiple times.

TODO: add some instances of such here for reference.

Implementation

Try to use cached version of data (e.g. validator set) from snapshot whenever possible.

[github-actions]

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[marcello33]

Do we need a JIRA task for this @manav2401 ?