Refactor code for better code contributing

[FeynmanZhou]

The code in the alpha version aims for functionality over quality. To ensure the code quality and maintainability. The following packages are required to be reviewed and refactored if necessary.

The following package list is generated by

go list -f '{{ join .Deps "\n" }}' ./cmd/ratify-gatekeeper-provider \
  | grep 'github.com/notaryproject/ratify/v2/' \
  | sed 's|github.com/notaryproject/ratify/v2/|- [ ] |'

Note

The reviewed / refactored packages are ticked.

• api/v2alpha1
• internal/cache
• internal/cache/inmemory
• internal/cache/ristretto
• internal/cloudprovider/azure
• internal/controller
• internal/encoding/jsonutil
• internal/executor
• internal/httpserver
• internal/httpserver/config
• internal/httpserver/tlssecret
• internal/manager
• internal/pod
• internal/policyenforcer
• internal/policyenforcer/threshold
• internal/store
• internal/store/credentialprovider
• internal/store/credentialprovider/azure
• internal/store/credentialprovider/static
• internal/store/filesystemocistore
• internal/store/registrystore
• internal/verifier
• internal/verifier/cosign
• internal/verifier/keyprovider
• internal/verifier/keyprovider/azurekeyvault
• internal/verifier/keyprovider/filesystemprovider
• internal/verifier/keyprovider/inlineprovider
• internal/verifier/notation