Redesign of `CodableTransaction` gas resolver

Within 3.0.0 all tx methods, properties etc were combined within CodableTransaction. This is quite rough decision and surely not the best one available.

Whilst there’s a room for improvement in many kinds, this issue focused on figuring out a good way to improve gas resolving related methods and properties.

So @janndriessen proposed to move resolver from within CodableTransaction object type to Web3Provider object, stating there it fits better.

This is good one, but to keep consistency within the lib we should to think as well about both tied to that resolvers parts of the library and the transaction sending pipeline itself.

Therefore I invite you folks to discuss the sending transaction as well as calling contract API pipeline design.

[janndriessen]

@yaroslavyaroslav @JeneaVranceanu @mloit please see #645 for a first draft PR.

[janndriessen]

Wouldn’t you just set the policy to manual and based on tx type the other policies would be ignored?

My point was to drop policies from within CodableTransaction totally. Like there’s only transaction gas properties left, but no Policies properties. But to keep automatic resolve features I suggest the way above, but it’s discussable for sure.

I like the idea. This would help CodableTransaction get clean and more simple (just a struct).

Checked again that only gasLimit and nonce policies actually use the transaction passed. So we could easily all do this in the resolver who already has the provider (as described in the outline above).