PB-1056 Tighten type checking rules

[msom]

The type checker is more useful when more checks are activated, as it allow to to checking for undefined attributes or missing overloads, for example.

I suggest that we enable some additional checks:

• enforce type definitions on methods (disallow_untyped_defs, disallow_incomplete_defs, disallow_untyped_decorators)
• check types within untyped methods (check_untyped_defs)
• show additional warnings for unused imports, missing return statements and unreachable code (warn_unused_ignores, warn_no_return, warn_unreachable)
• restrict equality checks to same types (strict_equality)

But only for our own code (ignore_missing_imports) and not for tests (exclude).

[asteiner-swisstopo]

General comment: Wouldn't it be easier to just set the strict mode and maybe disable things we absolutely don't want?

I had a go at this in branch sandbox-PB-1056-mypy-in-strict-mode (derived from this branch) and I had to adapt only very sensible things imho:
https://github.com/geoadmin/service-control/compare/feat-pb-1056-tighten-mypy..sandbox-PB-1056-mypy-in-strict-mode

Explicitly listing all the rules we want has the risk that mypy adds checks in the future and we don't add them here. Going with the --strict we are sure to always have them.

[msom]

Good idea to use strict per default and relax specific rules, but I would use strict in the config file, rather than the CLI as the config file will also be considered in vscode.

[msom]

@asteiner-swisstopo it's now as strict as your branch. I didn't use the monkeypatch part, as this results in a linting error. I think it's better to use a type:ignore here.

[schtibe]

Very nice, just a small question!

[asteiner-swisstopo]

Looks already pretty good, found some more opportunities to rely more on the default settings on strict mode.