Use partial signature messages instead of decided in exporter

[nkryuchkov]

The PR changes the exporter message handling logic to use partial signature messages instead of decided messages to gather information about consensus participants.

Since decided messages are not used anymore, the old API returning decided messages behaves a bit differently, constructing a "decided" message from information in the partial signature messages, but some fields are not available anymore, however, it's still compatible with the explorer, because it uses just a few fields. So, the old API is just a workaround for compatibility with the explorer.

There's also a new API that is simple/straightforward but requires changes to the explorer.

Examples of API:

Old

{"type":"decided","filter":{"from":1439466,"to":1439500,"role":"ATTESTER","publicKey":"aadcd9e473fa356a10dc14c876d1570d0f9affb39d479b317d39a93393d64b3608bb82220eb7011f659c5adc0275ac96"},"data":[{"Signature":null,"Signers":[29,30,31],"Message":{"MsgType":2,"Height":1439466,"Round":0,"Identifier":"AAAxEqrc2eRz+jVqENwUyHbRVw0Pmv+znUebMX05qTOT1ks2CLuCIg63AR9lnFrcAnWslgAAAAA=","Root":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"DataRound":0,"RoundChangeJustification":null,"PrepareJustification":null},"FullData":{"Duty":{"Type":0,"PubKey":"0x000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000","Slot":"1439466","ValidatorIndex":"0","CommitteeIndex":0,"CommitteeLength":0,"CommitteesAtSlot":0,"ValidatorCommitteeIndex":0,"ValidatorSyncCommitteeIndices":null},"Version":"unknown","PreConsensusJustifications":null,"DataSSZ":null}}]}

New

{"type":"participants","filter":{"from":1439466,"to":1439500,"role":"ATTESTER","publicKey":"aadcd9e473fa356a10dc14c876d1570d0f9affb39d479b317d39a93393d64b3608bb82220eb7011f659c5adc0275ac96"},"data":[{"Signers":[29,30,31],"Slot":"1439466","Identifier":"AAAxEqrc2eRz+jVqENwUyHbRVw0Pmv+znUebMX05qTOT1ks2CLuCIg63AR9lnFrcAnWslgAAAAA=","ValidatorPK":"aadcd9e473fa356a10dc14c876d1570d0f9affb39d479b317d39a93393d64b3608bb82220eb7011f659c5adc0275ac96","Role":"ATTESTER"}]}

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 19.33333% with 121 lines in your changes are missing coverage. Please review.

Project coverage is 50.1%. Comparing base (4867647) to head (cf2bf33). Report is 1 commits behind head on stage.

Files	Patch %	Lines
exporter/api/query_handlers.go	7.5%	49 Missing :warning:
exporter/api/msg.go	24.4%	37 Missing :warning:
ibft/storage/store.go	26.6%	32 Missing and 1 partial :warning:
cli/operator/node.go	0.0%	1 Missing :warning:
operator/validator/controller.go	50.0%	1 Missing :warning:

Additional details and impacted files

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[nkryuchkov]

The explorer team shared the fields they are using, so this PR needs to check whether all these fields are set in the old 'compatibiliy' API:

public key 
slot
role
version
network
round
height
signers
message_type 

[y0sher]

This was merged as part of #1409