[EFM] Modify DKG reactor engine and related logic to push IndexMap

[durkmurder]

Context

Each node participating in DKG uses a specific engine to drive the progress of DKG and as final step submits a tuple (dkgGroupkey, dkgParticipantKeys). In order to implement construction of IndexMap each node needs to submit their representation of IndexMap which establishes relation between NodeID -> DKG Index.

Definition of done

• Update DKG reactor engine to submit construct and submit IndexMap.
• Update tests

For extra details refer to parent issue: #6214

[durkmurder]

Completed in #6490