Automatically use mypy.ini or pyproject.toml when not in the root directory of the workspace

When using the Mypy linter, our standard is to have a `mypy.ini` in the project's root with a bunch of config values. Currently we have our developers use this setting for vscode:
```json
"python.linting.mypyArgs": [
"--config-file=${workspaceFolder}/mypy.ini"
]
```

_However, if a project doesn't have a `mypy.ini` file linting fails silently (which can cause a lot of issues as a dev might think that mypy worked fine)._

I think that auto-detecting and using the `mypy.ini` file should be a part of the plugin itself.

The issue concerns the VS Code mypy linter and its workspace configuration; no source file or test is named. Trace where the extension builds the mypy command, then verify behavior in a workspace with configuration in mypy.ini or pyproject.toml outside the workspace root. Done means configuration is detected automatically and missing configuration does not fail silently.

Written by the indexing model from the issue text.