CI: Add a scheduled dependency analysis job

FYI:
1. This job will be then used by 'buildkite-ci' and configured as a
'buildkite_pipeline_schedule' with a weekly frequently.
2. This job will also notify on the android-core-notifs slack channel
on a build failure.
3. This job has added custom meta-data for dependency analysis purposes.
This is done in order for it to be queried and easily identifiable
amongst other builds when working with the Buildkite's REST API.

.buildkite/schedules/dependency-analysis.yml

@@ -0,0 +1,23 @@
+# Nodes with values to reuse in the pipeline.
+common_params:
+  # Common plugin settings to use with the `plugins` key.
+  - &ci_toolkit
+      automattic/a8c-ci-toolkit#3.4.2
+
+agents:
+  queue: "android"
+
+steps:
+  - label: "dependency analysis"
+    # The meta-data added is used by Apps Metrics Prometheus collector to find the build.
+    command: |
+      buildkite-agent meta-data set "scheduled-build" "dependency-analysis"
+      echo "--- 📊 Analyzing"
+      cp gradle.properties-example gradle.properties
+      ./gradlew buildHealth
+    plugins: [*ci_toolkit]
+    artifact_paths:
+      - "build/reports/dependency-analysis/build-health-report.*"
+    notify:
+      - slack: "#android-core-notifs"
+        if: build.state == "failed"