Remove common models from SMF namespace and move them into common-src

Changes

• Remove all common-models from SMF directory and use the ones from common-src: oai-cn5g-common-src!23 (merged)
• Change the namespace of the common models

Further Refactors

• Correctly split SMF, PCF and NRF models should be done as next step

Note to reviewer

@tien-thinh.nguyen Most changes are just namespace changes and removing of the old models, in theory there should be no difference in the functionality at all.