CosmosFullNode should keep track of reference rpc heights.

[DavidNix]

Right now, this only benefits the height drift mitigation feature where we can check ref rpc heights along with the pod heights. There may be ways to leverage this feature for other features, but I'm unsure of specific examples at this time.

However, this adds more complexity.

• Ref data must be cached
• Configuring ref rpcs complicates configuration as a whole.
• Error handling as ref rpcs are can be flaky.
• Automatically pulling ref rpc data from chain registry.

[DavidNix]

I'm not sure if this is an important feature. It adds complexity and only powers height drift detection.