PXD-442 ⁃ auto-cast strings to proper type when appropriate

[frickjack]

sheepdog should be smart enough to auto-cast strings to the appropriate type (after validation) - so "11" gets cast to 11, or 11.0 gets cast to 11 for 'integer' type.

This kind of thing comes up a lot - ex: @cgmeyer reported

minor problem with using the form though:
when you enter an integer for, e.g., 4 for “number_of_melanomas_in_family”. when you click “upload submission json from form” it puts quotes around it (edited)
and then says it’s not an integer :

[trevars]

➤ profoak commented:

Is this similar to what we do on xml submission?

https://github.com/uc-cdis/sheepdog/blob/master/sheepdog/utils/transforms/bcr_xml_to_json.py#L704-L718

[philloooo]

yup, same concept, just do the auto-casting for json too