Ability to specify supported methods for a provider + chain

[chris13524]

Problem

Seems like different RPC providers support different methods, which results in flaky behavior where a method doesn't work sometimes.

Furthermore, a provider might support the method, but only on certain chains.

Proposed solution

Proposal is for each chain on a provider, to be able to specify what methods it supports. This would be factored into the load balancing algorithm to only include providers that support the user's requested method.

To make it more complex, we should include the method into the supported chains file. For example, if provider #1 supports the method but we do not have special rate limits with them, while provider #2 doesn't support the method but we do have a special rate limit, we should consider the method not highly available and disclose this.

Related to #698

[linear]

CR-481 Ability to specify supported methods for a provider + chain