revise query API on client

[mversic]

          I don't like it that on the http client we have API like `asset::all_definitions()`. Because it differs from what we have in smart contracts. IMO there is nothing wrong in constructing a query like this:

    let vec = client
        .query(FindAllAssetDefinitions::new())

Definitely not intended for this PR, but would like to get an opinion on this

Originally posted by @mversic in #4833 (comment)

[mversic]

in any case API should be the same in client and smart contract

[0x009922]

I don't see much usability in this module-based client construction, to be honest. Using structures like FindPeers is direct and easy enough, all names are unified, and IDE suggests them straight away.

Apart from that, I want to emphasise again the importance of having an async client (#3130). Current design of QueryBuilder is limited to sync QueryExecutor trait. Due to that, I had to re-implement a slice of client from scratch (https://github.com/soramitsu/iroha2-block-explorer-backend/blob/9d0a77161bf17336b307ee83fe77e8f91bb8704d/src/iroha.rs).

[aoyako]

I would like to work on this issue.