fix(middleware): oracles, tests

[DaniPopes]

Motivation

Old / non functioning API URLs

Solution

• Replace gas_now url (old redirected to new)
• deprecate eth_gas_station and replace it in docs and tests with gas_now
• temporarily ignore etherchain tests which is failing in builds due to 404
• clean up parsing and gas calculation since every oracle was different
• add some Default impls and other derives
• export internal Response structs which were exposed in the query functions but were not exported at mod level
• add common Result type alias for gas_oracle
• add missing tests for oracles
• big tests diffs are just removing indentation from removing unnecessary mod tests
• add missing fields in gas_now Response
• make file structure consistent with each other (imports -> definitions -> [trait impls, impls])

minor breaking changes:

• make blocknative API key optional, which also makes the estimatedBaseFees response field optional since I think a key is required for that
• change some base oracles' methods from request to query for consistency
• change all oracle query methods to return just the Response struct and move parsing in other functions

PR Checklist

• Added Tests
• Added Documentation
• Updated the changelog
• Breaking changes

[mattsse]

tysm!

It looks like this includes a lot of valuable but separate contributions, including some breaking changes I think.

I'd rather merge this in separate PRs, so it would be easier to merge this step by step.

Could you please split this as you see fit?

[DaniPopes]

What do you mean by easier to merge? I think a lot of these changes will overlap with each other which would have the opposite effect - I don't think there's much point in splitting this, it's mostly just making the individual oracles and file structure consistent + fixing a few bugs and adding a few tests

I finished listing all changes and breaking changes

[mattsse]

What do you mean by easier to merge? I think a lot of these changes will overlap with each other which would have the opposite effect - I don't think there's much point in splitting this

this is good to know.

I just wanted to check this, before looking at it more closely because it looks like it has a lot of valuable fixes.

[gakonst]

https://twitter.com/milancermak/status/1604441584808103936 maybe we can use this https://etherchain.org/api/gasnow, which redirects to https://beaconcha.in/api/v1/execution/gasnow