Provide code coverage metrics

[BernieWhite]

Ideally it would be great to generate code coverage metric from validation.

It would probably not be possible to generate metric from non-input files but where the validation relates to an input file it should be possible.

Other considerations:

• When files are generated from exports. i.e. Azure template file exports.
• Objects are currently not mapped to an extent in the source file.
• Some files might need to be excluded from the search path.