Refactor Archethic to leverage Archethic.Mining

I'm wondering if we should not move this function into the `Mining` context, so nested modules under `lib/archethic` will not call the top level `Archethic` but the siblings' context APIs.

Hence `Archethic` top level module will serve only `ArchethicWeb` which was the motivation around Phoenix contexts.

As `ArchethicWeb` doesn't need at all the `ContractContext`

_Originally posted by @samuelmanzanera in https://github.com/archethic-foundation/archethic-node/pull/1047#discussion_r1211914197_

Start by reviewing the context boundaries under lib/archethic, especially Archethic.Mining, the top-level Archethic module, ArchethicWeb, and ContractContext. Trace the function referred to in the issue and inspect the linked pull request discussion for its current location and callers. Done means nested modules use the Mining context API and ArchethicWeb no longer depends on ContractContext.

Written by the indexing model from the issue text.