This change makes it so that schemas can be replaced when they already exist.
This is to support the ability for kontainer drivers to update their dynamic
schemas.
Issue:
https://github.com/rancher/rancher/issues/17712
This change adds a dynamic field indicator to the field struct. This is so
we can remove the dynamic fields from an existing schema before merging the
dynamic schema and actual schema to prevent removed dynamic fields form being
incorrectly left behind on the schema.
Issue:
https://github.com/rancher/rancher/issues/12698