[Feature] minOccurs/maxOccurs representation

[fmigneault]

As per https://github.com/opengeospatial/ogcapi-processes/blob/master/core/openapi/schemas/inputDescription.yaml

minOccurs should always be an int
maxOccurs should always be an int or explicitly "unbounded"

Currently, the values are always returned as string.

We must return the process description according to the reference schema.
Because of pre-existing/deployed/remote processes, the conversion should be done in place such that values stored in db or read from remote instance are converted to int as needed before returning the process description.

During deployment, current behaviour that handles both numerical str or int should remain valid such that it doesn't break existing request contents. Future deployments should transparently convert the items as applicable.