[cmd/opampsupervisor] Add integration/E2E tests (#27002)

**Description:**

Add tests that verify the Supervisor's behavior using a real Collector
binary against an OpAMP server written with the opamp-go library. This
tests a basic set of functionality mostly based on what is currently
listed as implemented in the Supervisor's feature table.

Right now these tests start the Supervisor using the Go API to avoid
process handling, but could be changed to start it through a binary in
the future. I've placed these tests in the E2E testing workflow even
though they run fairly quickly since they depend on a built Collector
binary, may become more expansive in the future, and don't fit in any of
the existing jobs in the `build-and-test` workflow. I'm open to placing
them in another location if we'd prefer them elsewhere.

This also updates opamp-go to v0.9.0 to take advantage of
open-telemetry/opamp-go#200.

**Link to tracking Issue:**

Resolves
#24292

.github/workflows/e2e-tests.yml

@@ -12,7 +12,7 @@ env:
   # We limit cache download as a whole to 5 minutes.
   SEGMENT_DOWNLOAD_TIMEOUT_MINS: 2
 jobs:
-  docker-build:
+  collector-build:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
@@ -33,6 +33,40 @@ jobs:
       - name: Install dependencies
         if: steps.go-cache.outputs.cache-hit != 'true'
         run: make -j2 gomoddownload
+      - name: Build Collector
+        run: make otelcontribcol
+      - name: Upload Collector Binary
+        uses: actions/upload-artifact@v3
+        with:
+          name: collector-binary
+          path: ./bin/*
+  docker-build:
+    runs-on: ubuntu-latest
+    needs: collector-build
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - uses: actions/setup-go@v4
+        with:
+          go-version: ~1.20.8
+          cache: false
+      - name: Cache Go
+        id: go-cache
+        timeout-minutes: 5
+        uses: actions/cache@v3
+        with:
+          path: |
+            ~/go/bin
+            ~/go/pkg/mod
+          key: go-cache-${{ runner.os }}-${{ hashFiles('**/go.sum') }}
+      - name: Install dependencies
+        if: steps.go-cache.outputs.cache-hit != 'true'
+        run: make -j2 gomoddownload
+      - name: Download Collector Binary
+        uses: actions/download-artifact@v3
+        with:
+          name: collector-binary
+          path: bin/
       - name: Build Docker Image
         run: |
           make docker-otelcontribcol
@@ -107,3 +141,35 @@ jobs:
         run: |
           cd receiver/k8sobjectsreceiver
           go test -v --tags=e2e
+  supervisor-test:
+    runs-on: ubuntu-latest
+    needs: collector-build
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v4
+        with:
+          go-version: ~1.20.8
+          cache: false
+      - name: Cache Go
+        id: go-cache
+        timeout-minutes: 5
+        uses: actions/cache@v3
+        with:
+          path: |
+            ~/go/bin
+            ~/go/pkg/mod
+          key: go-cache-${{ runner.os }}-${{ hashFiles('**/go.sum') }} 
+      - name: Install dependencies
+        if: steps.go-cache.outputs.cache-hit != 'true'
+        run: make -j2 gomoddownload
+      - name: Download Collector Binary
+        uses: actions/download-artifact@v3
+        with:
+          name: collector-binary
+          path: bin/
+      - run: chmod +x bin/*
+      - name: Run opampsupervisor e2e tests
+        run: |    
+          cd cmd/opampsupervisor
+          go test -v --tags=e2e
+

cmd/opampsupervisor/Makefile

@@ -1 +1,5 @@
 include ../../Makefile.Common
+
+e2e-test:
+	make -C ../../ otelcontribcol
+	go test -v --tags=e2e .