Iam 160 create charmed operator

[bencekov]

I rectified most comments. I have not included the changes, where I left a comment detailing why. If this PR is approved, I'll delete the previous one.

Updates not done:

• Didn't take out function that returns service url. I use it while developing the integrations.
• Didn't remove port var from config. This is consistent with application where the working port is configurable with envvar.
• Took out integration test code, and integration test environmet from tox.ini. I'm not done with the integration tests, I'll include them with the pr including the relations.

[nsklikas]

Please fix the linting errors and the github workflows.

[natalian98]

you can add the publish action now - it should only run on push, so when this PR will be approved and merged

[natalian98]

Could you update pyproject.toml to reflect settings from other repos? Like here. I think it may solve some of the lint errors that we chose to ignore.
For example, current pyproject.toml specifies e.g. line length for ruff, but you are using isort and flake8. This is why you get a lot of errors saying your line should not exceed the default 79 characters and they don't disappear after you run black - it aims for 99 characters. With this file updated, the respected length will be 99 chars.

[natalian98]

lgtm