Add targets into main function

We need a way of raising an exception and warning when thresholds aren't met (global or by module).

For example:

```
python -m ansys.tools.example_coverage -f "path_to_package" --error_thresh 50 --warn_thresh 80
```

This will raise an error if global coverage is below 50% and a warning if below 80%.

Could also implement in a modules by module basis:
```
python -m ansys.tools.example_coverage -f "path_to_package" --error_thresh_module 50 --warn_thresh_module 80
```

---
Consider having a configuration file to make this easier to configure (ignoring regex, etc).

Start at the main function behind `python -m ansys.tools.example_coverage` and trace how command-line options are parsed. Define completion as global and per-module error and warning thresholds producing the requested outcomes; the optional configuration-file behavior still needs scope and a project decision.

Written by the indexing model from the issue text.