Add retries to RPC clients

[cam-schultz]

Context and scope
It's currently up to the caller to implement retry loops when making RPC calls via packages such as ethclient. We should provide utilities or extensions that wrap RPC calls with retries handled automatically.

Discussion and alternatives

• We should investigate adding a generic utility that takes a function to be called in a retry loop, and a set of parameters dictating how retries are handled.
• We should consider integrating exponential backoff (rather than constant or linearly increasing retry intervals). Packages such as https://pkg.go.dev/github.com/cenkalti/backoff/v4 provide this out of the box.

Open questions
Questions that are still being discussed.