feat: eth_call builder

[prestwich]

Depends on #644

Motivation

Partially addresses #613

Solution

• Implement a basic builder returned by Provider::call that allows configuration of the
• delete call_with_overrides
• remove block arg from Provider::call

If we like the pattern we can apply it to the other rpc reqs that take BlockId as optional param

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes

[prestwich]

cc @DaniPopes i don't love the amount of lifetime complexity i added to the call with decoder, but it should be invisible to users pretty much all the time i think?

[prestwich]

Notes on why this level of complexity:

• 'client - we use ClientRef instead of WeakClient because IntoFuture impl would otherwise require upgrading inside into_future() in an awkward way
• 'req - we borrow the request so that it can be reused for concurrent calls with other overrides, and for sending. this is also consistent with the provider interface
• 'state - we borrow the state to avoid cloning it, as the clone may be expensive. this also allows it to be used with other concurrent calls. Future we may want to allow state to be a RawValue so that users can share it between calls and also avoid serializing it each time
• 'coder - we borrow the coder to be consistent with behavior before this PR

[prestwich]

okay I have removed the 'client lifetime by making an intermediate future type that handles upgrading a WeakClient

[onbjerg]

lgtm, nicer than having call_with_overrides

[onbjerg]

beautiful