Describe the bug
Currently, data prepper does not validate that routes exist on startup, and even during runtime will not throw any errors.

To Reproduce
Steps to reproduce the behavior:
Create a config like

routes:
    - route_one: '/my_route == 10'
    - route_two: '/my_route == 11'
  sink:
    - pipeline:
        name: "sub-pipeline-1"
        routes:
          - FIRST_ROUTE
    - pipeline:
        name: "sub-pipeline-2"
        routes:
          - SECOND_ROUTE

None of the data will be routed to either pipeline, and there will be no errors or validations

Expected behavior
Throw a validation error when a route is defined in the sink that does not exist. For the above, this may look like

Route "FIRST_ROUTE" does not exist. Configured routes include [resources_route, resource_route]

Screenshots
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Environment (please complete the following information):

• OS: [e.g. Ubuntu 20.04 LTS]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.