Validator - support partitioning of the slot id space

[marcinczenko]

This PR, addresses issue #457 (please refer to the issue discussion for more context info so that we do not have to duplicate it all here).

To shortly summarise issue #457: we want to be able to tell the validator what partition of the whole slot id space it should observe and help validating.

To achieve that, we provide two new CLI/config parameters:

• validator-partition-size - to indicate number equal partitions dividing the whole slot id space,
• validator-partition-index - to indicate the index of the portion observed by the validator.

The validator will only consider a slot with slot id slotId for validation if it matches the following criteria:

slotId % validatorPartitionSize == validatorPartitionIndex

We decided to keep the --validator-max-slots option to additionally limit the number of slots that will be observed by the validator for the chosen slot id partition.

To be done in this PR:

• add new CLI/config options
• add the corresponding partitioning params to the validation object,
• incorporate portioning logic in the validator,
• extend the validation tests to cover partitioning
• refactor validation params into separate type for cleaner validation
• updated relevant documentation (specifically where the cmd line params are mentioned).

[emizzle]

Overall, great job! 👏

I have a few (detailed) comments, mostly because I had already gone through the mental hurdles of this task in the past, so I knew of some nuances.

[emizzle]

Looking good, Marcin! I'll approve now as there is nothing blocking.

On a formatting note, it would be good if you could limit line length to 80 chars please 🙏

[marcinczenko]

Looking good, Marcin! I'll approve now as there is nothing blocking.

On a formatting note, it would be good if you could limit line length to 80 chars please 🙏

Will be done.