MyPy: Add the check-untyped-defs option for mypy.

[GuillaumeCrowdcomfort]

Description

• Add the ability to specify check-untyped-defs in the options section for mypy.

Related Issue

Feature request: #628

Motivation and Context

It is not required, but helping with better code quality is excellent.

How Has This Been Tested?

The protocol followed has been:

• Create a file with a function without types
• Run the current prospector version.
• Get the message "By default, the bodies of untyped functions are not checked. Consider using --check-untyped-defs [annotation-unchecked]"
• Apply the changes from the PR.
• Add the option check-untyped-defs in the prospector.yaml such as:

mypy:
  run: true
  options:
    ignore-missing-imports: true
    check-untyped-defs: true

• Install it locally with python3 install -e .
• Rerun, the prospector.
• Get correct type inferences and checks.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• My change requires a change to the dependencies
• I have updated the dependencies accordingly
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All existing passing tests passed.
• All new and existing tests passed.