Create a test that sends a transaction for each shutterized block

[ylembachar]

Motivation
Send a transaction for every shutterized block to understand the inclusion success and failure rates for every shutterized block, i.e. we need every block to include the transactions it was supposed to include.

Steps

1. Query the validator registry to get the list of registered validators
2. Query the consensus node to get the list of next proposers
3. If one of the proposers is a registered validator, send the transaction at the beginning of the epoch, and expect it to be included within that slot. If more than one proposer is a registered validator, send the first transaction at the beginning of the slot, the second one immediately after the registered slot, and so on.

Additional information

• epoch = 16 slots / slot = 5s
• we can potentially reuse code from here:
• https://github.com/shutter-network/rolling-shutter/blob/d36053340e1af0a2afaa6be4bfaf3b5a7eb92ddd/rolling-shutter/medley/validatorregistry/validatorregistry.go#L1
• and here: https://github.com/shutter-network/rolling-shutter/blob/d36053340e1af0a2afaa6be4bfaf3b5a7eb92ddd/rolling-shutter/keyperimpl/gnosis/validatorsyncer.go#L31