feat: Add Access Token callback Vault token reload

[lenny-goodell]

If your build fails due to your commit message not passing the build checks, please review the guidelines here: https://github.com/edgexfoundry/go-mod-bootstrap/blob/main/.github/Contributing.md

PR Checklist

Please check if your PR fulfills the following requirements:

• I am not introducing a breaking change (if you are, flag in conventional commit message with BREAKING CHANGE: describing the break)
• I am not introducing a new dependency (add notes below if you are)
• I have added/updated unit tests for the new feature or bug fix (if not, why?)
• I have fully tested (add details below) this the new feature or bug fix (if not, why?)
• I have opened a PR for the related docs change (if not, why?) internal, not applicable

Testing Instructions

1. Start edgex using compose builder using make run
2. This will create the SecretStore for app-rules-engine
3. Stop the App Rules Engine container
4. Clone branch for this PR
5. Add the following to app-functions-sdk-go go.mod

replace (
	github.com/edgexfoundry/go-mod-bootstrap/v2 => ../go-mod-bootstrap
)

6. Add the following to app-service-configurable go.mod

replace github.com/edgexfoundry/app-functions-sdk-go/v2 => ../app-functions-sdk-go

replace github.com/edgexfoundry/go-mod-bootstrap/v2 => ../MODS/go-mod-bootstrap

7. Build app service configurable. make build
8. Run app service configurable with following command

 sudo EDGEX_SECURITY_SECRET_STORE=true ./app-service-configurable  -cp -r -p=rules-engine -o

9. Restart Security Store Setup container
10. From Consul set edgex/appservices/2.0/app-rules-engine/Writable/LogLevel to DEBUG
11. Verify logs show following

level=INFO ts=2021-10-12T21:17:17.1307442Z app=app-rules-engine source=secrets.go:284 msg="context cancelled, dismiss the token renewal process"
level=INFO ts=2021-10-12T21:17:17.1337049Z app=app-rules-engine source=secrets.go:276 msg="kick off token renewal with interval: 30m0s"
level=INFO ts=2021-10-12T21:17:17.1567656Z app=app-rules-engine source=secrets.go:148 msg="successfully generated Consul token for service app-rules-engine"
level=INFO ts=2021-10-12T21:17:17.1568642Z app=app-rules-engine source=config.go:159 msg="Using Configuration Provider access token of length 36"
level=INFO ts=2021-10-12T21:17:17.1602663Z app=app-rules-engine source=config.go:479 msg="Writeable configuration has been updated from the Configuration Provider"
level=INFO ts=2021-10-12T21:17:17.1603564Z app=app-rules-engine source=config.go:485 msg="Logging level changed to DEBUG"

12. Restart Security Store Setup container
13. Send the following JSON to http://localhost:59701/api/v2/secret

{
  "apiVersion": "v2",
  "path" : "mqtt2",
  "secretData" : [
    {
      "key" : "username",
      "value" : "app-user"
    },
    {
      "key" : "password",
      "value" : "SuperDuperSecretPassword"
    }
  ]
}

14. Verify 201 status returned and logs show following

level=DEBUG ts=2021-10-12T21:56:03.8954831Z app=app-rules-engine source=secrets.go:420 msg="Using Secrets URL of `http://localhost:8200/v1/secret/edgex/app-rules-engine/mqtt2`"
level=INFO ts=2021-10-12T21:56:03.8988297Z app=app-rules-engine source=secrets.go:284 msg="context cancelled, dismiss the token renewal process"
level=DEBUG ts=2021-10-12T21:56:03.9061821Z app=app-rules-engine source=secrets.go:420 msg="Using Secrets URL of `http://localhost:8200/v1/secret/edgex/app-rules-engine/mqtt2`"
level=INFO ts=2021-10-12T21:56:03.9062945Z app=app-rules-engine source=secrets.go:276 msg="kick off token renewal with interval: 30m0s"

15. Restart Security Store Setup container
16. Press CRTL C to stop app service
17. Verify logs show following

^Clevel=INFO ts=2021-10-12T21:59:14.6273139Z app=app-rules-engine source=secrets.go:284 msg="context cancelled, dismiss the token renewal process"
level=INFO ts=2021-10-12T21:59:14.6273829Z app=app-rules-engine source=telemetry.go:83 msg="Exiting CPU Usage Average loop"
level=INFO ts=2021-10-12T21:59:14.6273512Z app=app-rules-engine source=messaging.go:123 msg="Exiting waiting for MessageBus 'edgex/events/#' topic messages"
level=INFO ts=2021-10-12T21:59:14.6272992Z app=app-rules-engine source=service.go:200 msg="Terminating signal received: interrupt"
level=INFO ts=2021-10-12T21:59:14.6274061Z app=app-rules-engine source=configupdates.go:62 msg="Exiting waiting for App Service configuration updates"
level=INFO ts=2021-10-12T21:59:14.6273722Z app=app-rules-engine source=messaging.go:139 msg="Exiting waiting for MessageBus errors and background publishing"
level=INFO ts=2021-10-12T21:59:14.627462Z app=app-rules-engine source=config.go:449 msg="Watching for '/Writable' configuration changes has stopped"
level=INFO ts=2021-10-12T21:59:14.6276276Z app=app-rules-engine source=bootstrap.go:135 msg="Un-Registering service from the Registry"
level=INFO ts=2021-10-12T21:59:14.6360734Z app=app-rules-engine source=secrets.go:276 msg="kick off token renewal with interval: 30m0s"
level=INFO ts=2021-10-12T21:59:14.6361582Z app=app-rules-engine source=secrets.go:284 msg="context cancelled, dismiss the token renewal process"
level=INFO ts=2021-10-12T21:59:14.6500755Z app=app-rules-engine source=secrets.go:148 msg="successfully generated Consul token for service app-rules-engine"
level=INFO ts=2021-10-12T21:59:14.6501655Z app=app-rules-engine source=registry.go:62 msg="Using Registry access token of length 36"
level=INFO ts=2021-10-12T21:59:14.6521669Z app=app-rules-engine source=messaging.go:168 msg="Disconnecting from the message bus"

New Dependency Instructions (If applicable)

N/A

[jim-wang-intel]

LGTM except very tiny issue about extra comment

[lenny-goodell]

recheck