refactor norm-type/statistics mlm:input properties

[fmigneault]

Description

• Adds the scaling field to replace the combination of norm_type, norm_clip, norm_by_channel and statistics field combinations under a common definition.
• Adds better validation of expected sub-fields by each scaling type.

Related Issue

• fixes Add explicit dependency checks for normalization details #26

Type of Change

• 📚 Examples, docs, tutorials or dependencies update;
• 🔧 Bug fix (non-breaking change which fixes an issue);
• 🥂 Improvement (non-breaking change which improves an existing feature);
• 🚀 New feature (non-breaking change which adds functionality);
• 💥 Breaking change (fix or feature that would cause existing functionality to change);
• 🔐 Security fix.

Checklist

• I've read the CONTRIBUTING.md guide;
• I've updated the code style using make check;
• I've written tests for all new methods and classes that I created;
• I've written the docstring in Google format for all the methods and classes that I used.

[rbavery]

Looks good! looking forward to clearer semantics for applying statistics (no value_scaling) to inputs.