* Adds validatorPartitionSize and validatorPartitionIndex config options
* adds partitioning options to the validation type
* adds partitioning logic to the validator
* ignores partitionIndex when partitionSize is either 0 or 1
* clips the partition index to <<partitionIndex mod partitionSize>>
* handles negative values for the validation partition index
* updates long description of the new validator cli options
* makes default partitionSize to be 0 for better backward compatibility
* Improving formatting on validator CLI
* reactors validation params into a separate type and simplifies validation of validation params
* removes suspected duplication
* fixes typo in validator CLI help
* updates README
* Applies review comments - using optionals and range types to handle validation params
* Adds initializer to the configFactory for validatorMaxSlots
* [Review] update validator CLI description and README
* [Review]: renaming validationParams to validationConfig (config)
* [Review]: move validationconfig.nim to a higher level (next to validation.nim)
* changes backing type of MaxSlots to be int and makes sure slots are validated without limit when maxSlots is set to 0
* adds more end-to-end test for the validator and the groups
* fixes typo in README and conf.nim
* makes `maxSlotsConstraintRespected` and `shouldValidateSlot` private + updates the tests
* fixes public address of the signer account in the marketplace tutorial
* applies review comments - removes two tests
* updates Marketplace tutorial documentation
* Applies review comments to marketplace-tutorial
* Final formatting touches
* moved `Prerequisites` around
* Fixes indentation in one JSON snippet
Marcin Czenko
Giuliano Mega