Refactor structure of tribler communities

[drew2a]

This PR contains refactoring of tribler's communities structure.

An attempt has been made to bring the structure to the following:

modules
├my_community
  ├ tests
  | └test*.py
  ├ community.py
  └ settings.py

The core idea is to make communities more unified (by bringing them to a uniform structure) and more autonomous (by combining implementation with its settings definition)

Implementation

For each Tribler community settings field has been added by inheriting them from:

class TriblerCommunity(Community):
    def __init__(self, *args, settings: TriblerConfigSection = None, **kwargs):
        super().__init__(*args, **kwargs)
        self.settings = settings

The settings set in ipv8_module_catalog.py for a normal Tribler's run:

class MyCommunityLauncher(IPv8CommunityLauncher):
    def get_kwargs(self, session):
        return {
            'settings': session.config.my_community,
        }

For tests it can be done by passing a settings object into community constructor:

mock_ipv8.overlay.my_community = MyCommunity(settings=BandwidthAccountingSettings())

Problems

I've encountered problems during refactoring the following entities:

1. TunnelCommunity
2. MetadataStore

TunnelCommunity

Tribler's TunnelCommunity highly intertwined with Ipv8's TunnelCommunity and looks like hi-level "hack" or "patch" (I guess this is the result of an epic Dispersy refactoring).
Therefore it is hard to control and modify, for example, Community settings.

This PR leaves TunnelSettings as is, adding only the following logic in TriblerTunnelCommunityLauncher:

class TriblerTunnelCommunityLauncher(IPv8CommunityLauncher):
    def get_kwargs(self, session):
        from ipv8.messaging.anonymization.community import TunnelSettings

        settings = TunnelSettings()
        settings.min_circuits = session.config.tunnel_community.min_circuits
        settings.max_circuits = session.config.tunnel_community.max_circuits

MetadataStore

MetadataStore is a very special place in Tribler which is unlike anything else. It uses a special structure and special inner logic.
This unit contains two communities, ORM bindings, and REST-API.

It contains also RemoteQueryCommunity which is the base class for PopularityCommunity and GigaChannelCommunity. These dependencies make it difficult to isolate atomic settings for each community.

This PR leaves MetadataStore almost as-is, leaving refactoring to the author, except for:

1. RemoteQueryCommunity extracted from MetadataStore and placed to modulesalong with the rest communities.
2. Has been added rqc_settings field to RemoteQueryCommunity class and all its successors.

class RemoteQueryCommunity(TriblerCommunity, EVAProtocolMixin):
    def __init__(self, my_peer, endpoint, network, metadata_store, rqc_settings: RemoteQueryCommunitySettings = None,
                 **kwargs):
        super().__init__(my_peer, endpoint, network=network, **kwargs)
        self.rqc_settings = rqc_settings or RemoteQueryCommunitySettings()

Launcher:

class PopularityCommunityLauncher(IPv8CommunityLauncher):
    def get_kwargs(self, session):
        return {
            'settings': session.config.popularity_community,
            'rqc_settings': session.config.remote_query_community,
        }

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
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0.0% Duplication

[synctext]

Good initiative!
You are merging and unifying the coding practices of several Tribler communities (e.g. Lab members). That's never going to be easy 👏

[ichorid]

This PR leaves MetadataStore almost as-is, leaving refactoring to the author ...

“The proof is left up to the student” (c) Richard Feynman 🤣

[egbertbouman]

Looks like we just commited some test artifacts (0.db and 1.db) to our main branch...

[drew2a]

@egbertbouman yes, you are right. Will fix it soon.
Related to #6158