Revamp modules/package structure

[llucax]

What's needed?

We need to have a consistent modules and packages structure, so:

1. imports are clean and clear
2. Chances of ending with cyclic imports are minimized or completely removed (Resolve potential cyclic import issues #84)
3. We minimize the amount of unused code that is indirectly imported
4. The generated documentation makes sense (see the issue in Evaluate if we want to use google-style imports or not frequenz-repo-config-python#56 for example)
5. Logging makes sense

Proposed solution

This is still to be researched and decided.

Use cases

No response

Alternatives and workarounds

No response

Additional context

There are a few other issues related to this topic:

• Enforce Google-syle imports #222

  With the current import structure, this doesn't always make sense, for example we have a config module/package. Using names that are so generic are not always that clear with this scheme, as the user could also have some module called config.

  Related issues and discussions:

  • Evaluate if we want to use google-style imports or not frequenz-repo-config-python#56
  • Start following Google style imports #209
  • Make pylint check for Google style imports frequenz-repo-config-python#14 (it would be good to check what kind of enforcement this does before going for this)

• Add modules for each component component in frequenz.sdk.microgrid  #118

  Is assuming we use google-style imports.

• Point 3 (minimize the amount of unused code that is indirectly imported) is also important. Since Python executes the code, and importing a modules can have arbitrary code execution, importing could be very expensive, and it could happen that just to import a small utility function, you end up importing the whole SDK, so it would be good to have this in consideration when thinking about a package/modules structure.

• Point 5: 5. Logging normally uses the module name as logger. This means that logs produced in private modules for example (like package.some._module), the logger name will be weird, it will show package.some._module instead of the public module where symbols are exported (package.some).

• Restructure timeseries module #704