refactor(20148): Add a feature flag to disable behaviour policies

[vanch3d]

See https://hivemq.kanbanize.com/ctrl_board/57/cards/20148/details/

The PR adds a feature flag (VITE_FLAG_DATAHUB_PROTOBUF_ENABLED) to disabled the behavior policies from the frontend:

• Behavior policies are not listed on the Data Hub table
• Drag-and-drop icons for the behavior policy and transition nodes are hidden in the toobar

By default, the flag is disabled. To change the flag, edit your .env.local (or .env for a github release) with the following property:

VITE_FLAG_DATAHUB_BEHAVIOR_ENABLED=true

Before

After