review: HETHRateProvider

[rabmarut]

Closes #23.

This review produced two findings, one Medium and one Low, which must be addressed prior to Balancer integration.

• M01: Price updates are effectively unbounded due to lack of time-based constraint
• L01: Implementation contract for StakingConfiguration is unverified on etherscan

[s2imonovic]

L01: Resolved. https://etherscan.io/address/0x51B2f83aac13adB9Ed826C4cdb593C88e6B61C92
M01: The mechanism currently in place on our backend for updating the consensus layer's (validator) balance operates by considering only the change in balance percentage on the consensus as the sole relevant factor for triggering an action. The element of time does not influence this process. We do have the option to introduce a limitation, whereby the function for setting the state can only be called once every X days. However, this is not as relevant as when we make the calls based on changes in percentages on the consensus layer, which can occur multiple times throughout the hour/day/week.