Rosetta Implementation - pt2 FIX2 (Stage 3.2 of Node API Overhaul)

[Daniel-VDM]

Stage 3.2 FIX2 of Node API Overhaul

This PR is related to #3312 .

TLDR: This fixes the Undelegation reward operation as well as correctly accounts for the redelegation balance changes. This also adds an info dump for the last block that was garbage collected for non-archival DBs.

Details

Previously, the Undelegation transaction would result in a balance changing operation (other than gas). As this is not the case due to the locking period, the balance at a given block could be different than what it is on-chain. Therefore a 'special' transaction is added to the implementation to account for the Undelegation payouts at the last block of an epoch (similar to the pre-staking era block rewards).

Note that all nodes (archival & pruned) store the last block of an epoch, however, the Undelegations saved for the said block are after the Undelegations have been paid out. Since the unpaid Undelegations are needed to recompute the paid out amount for each delegator, the state of the second to the last block of an epoch is required. This means that the non-archival nodes/DBs will not be able to provide this data unless the state is still in memory. This is why I have added the 'oldest block identifier' on the network endpoint for nodes running in the non-archival mode.

The oldest block number is computed from the biggest block number that has been garbage collected plus 1. Since the block garbage collection is done monotonically w.r.t. block number, this should always give a block number that is in memory.

Lastly, I used the transaction receipt to report how much of the redelegation took from the account's balance. As well as did some general refactoring/clean-up given the new functions & variables.

All logic was tested using localnet as well as testnet using the rosetta-cli.

[codecov]

Codecov Report

Merging #3338 into main will decrease coverage by 0.07%.
The diff coverage is 22.42%.

@@            Coverage Diff             @@
##             main    #3338      +/-   ##
==========================================
- Coverage   34.38%   34.30%   -0.08%     
==========================================
  Files         209      209              
  Lines       24906    25020     +114     
==========================================
+ Hits         8564     8584      +20     
- Misses      15685    15785     +100     
+ Partials      657      651       -6     

Impacted Files	Coverage Δ
rosetta/common/errors.go	0.00% <0.00%> (ø)
rosetta/services/network.go	40.80% <0.00%> (-3.85%)	⬇️
core/blockchain.go	8.17% <11.11%> (-0.23%)	⬇️
rosetta/services/block.go	46.44% <26.11%> (-3.12%)	⬇️

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