Is your feature request related to a problem? Please describe.

linkml-convert doesn't accept children of a class specified in a range as valid. Being used to the behavior of inheritance in OOP that also applies to the generated Python code, I find it misleading and frustrating.

Describe the solution you'd like
IMO (point of view of an OOP programmer, might be different for an "ontologist") accepting children should be the default behavior. Since gen-json-schema and linkml-validate already have the option --include-range-class-descendants, having such an option for linkml-convert would be also fine for me.

How important is this feature? Select from the options below:
• Medium - As of now I have to ignore validation errors that appear due to this limitation of linkml-convert

When will use cases depending on this become relevant? Select from the options below:
• Short-term - 2-4 weeks

Additional context
I'm providing a PR to implement this feature.