code cleaning

build/scripts/build_helper.fb_folly

build/scripts/build_helper.nssf

build/scripts/build_nssf

docker/Dockerfile.nssf.rhel8

docker/Dockerfile.nssf.ubuntu18

docs/FEATURE_SET.md

etc/nssf.conf

etc/nssf_local_conf.json

etc/nssf_slice_config.json

scripts/docker-compose.yaml

scripts/entrypoint.sh

src/api-server/api/NFInstanceIDDocumentApi.cpp

src/api-server/api/NFInstanceIDDocumentApi.h

src/api-server/api/NSSAIAvailabilityStoreApi.cpp

src/api-server/api/NSSAIAvailabilityStoreApi.h

src/api-server/api/NetworkSliceInformationDocumentApi.cpp

src/api-server/api/NetworkSliceInformationDocumentApi.h

src/api-server/api/SubscriptionIDDocumentApi.cpp

src/api-server/api/SubscriptionIDDocumentApi.h

src/api-server/api/SubscriptionsCollectionApi.cpp