Add Control plane integration test

[stevenwarejones]

Adds an In Process test

1. Set up data watcher
2. Set up Vid Labeler
3. Write input events to data watcher
4. Data watcher matches events and calls control plane
5. Vid Labeler finds and executes work from control plane
6. Verify labeled data

Depends on #1991

[wfa-reviewable]

This change is 

[SanjayVas]

Reviewable status: 0 of 21 files reviewed, 1 unresolved discussion (waiting on @kungfucraig, @Marco-Premier, and @stevenwarejones)

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a discussion (no related file):
Base this PR branch on the dependent PR branch and set the base on the PR in GitHub. See #1991 (review)

[stevenwarejones]

Reviewable status: 0 of 21 files reviewed, 1 unresolved discussion (waiting on @kungfucraig, @Marco-Premier, and @SanjayVas)

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a discussion (no related file):

Previously, SanjayVas (Sanjay Vasandani) wrote…

Base this PR branch on the dependent PR branch and set the base on the PR in GitHub. See #1991 (review)

Done.

[kungfucraig]

Reviewable status: 0 of 21 files reviewed, 2 unresolved discussions (waiting on @Marco-Premier, @SanjayVas, and @stevenwarejones)

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src/test/kotlin/org/wfanet/measurement/securecomputation/ControlPlaneIntegrationTest.kt line 101 at r4 (raw file):

      val inMemoryStorageClient = InMemoryStorageClient()
      val subscribingStorageClient = GcsSubscribingStorageClient(inMemoryStorageClient)
      val vidLabelerApp =

Creating an "echo app" and using it here would be nice. Then you don't get caught up having to update this test as the VID Labeler App evolves, which surely it will. Plus an EchoApp would provide a nice example for people to work from.