Allow plugin configuration from Vizier definition/flags

[aimichelle]

Is your feature request related to a problem? Please describe. Enabling a plugin currently requires a user to enable the plugin through the UI or make a gRPC request through the API. In some cases, users may want to enable the plugin for a Vizier at deploy-time (for example, using a k8s manifest).

Describe the solution you'd like Add plugin configuration to a Vizier's configuration (for example, a CRD). Upon deploy or any changes, Vizier can notify the control plane of any enabled/disabled plugins. The control plane is then responsible for configuring the plugin and running the correct export scripts.