refactor: init, utilities, and test envs

[Keyrxng]

During the initial build review everything was made to be null rather than optional which makes it a mess when initializing rpc-handler because everything must be explicitly set to null or non-null.

We should make all of the nullable init values optional to make it easier for the end user to set things up by removing the burden of having to consider if they actually need to define runtimeRpcs (which they don't) etc.

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Maybe it would be helpful to build a utility class with the various helper functions already built and consider if there is a need for any others?

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Since pay.ubq.fi tests has been a point of contention and it's likely to be used elsewhere too, we could build an Anvil module similar to the one used for testing there and beef it up to include more redundancies like caching the intended steps and if we fail kill and spawn another and rerun the script.

Idk if we can mess with Anvil at a low level, I know I can't, but other than that I don't see a clear solution to that problem from a rpc-handler perspective.