feat: standardize method naming conventions in API Classes

[luboszima]

Is your feature request related to a problem? Please describe.

feat/chore

Describe the solution you'd like

While working with the synology_api/docker_api.py class, I noticed that many methods are named with different conventions, and there is no consistent terminology or naming standard throughout the class.

See my original comment: #241 (comment)

This feature aims to establish a standard for method naming in our API classes and ensure backward compatibility with existing method names.

Additional context

I suggest using a format like:

<api_method>_<api_area>()

Where api_method refers to the WebAPI method (e.g., list, get, stats), and api_area is a formatted API name. For example:

$ echo "SYNO.Docker.Image" | sed 's/SYNO.//' | tr '.' '_' | tr '[:upper:]' '[:lower:]'
docker_image

Note: if api_method is list or some get which returns multiple elements/data we can add plural s behind api_area

TODO

• Our classes use standardized naming
• We maintain backward compatibility
• Optional: Add a GitHub Actions workflow to test the naming convention