chore(librarian): onboard google-cloud-video-stitcher to librarian (#14618)

Now that `rest` is enabled for this API in the bazel config, we're
onboarding `google-cloud-video-stitcher` to librarian.

Towards googleapis/librarian#762

Author: ohmayr

.librarian/state.yaml

@@ -1778,3 +1778,21 @@ libraries:
     remove_regex:
       - packages/google-cloud-workflows
     tag_format: '{id}-v{version}'
+  - id: google-cloud-video-stitcher
+    version: 0.7.18
+    last_generated_commit: d300b151a973ce0425ae4ad07b3de957ca31bec6
+    apis:
+      - path: google/cloud/video/stitcher/v1
+    source_roots:
+      - packages/google-cloud-video-stitcher
+    preserve_regex:
+      - packages/google-cloud-video-stitcher/CHANGELOG.md
+      - docs/CHANGELOG.md
+      - docs/README.rst
+      - samples/README.txt
+      - scripts/client-post-processing
+      - samples/snippets/README.rst
+      - tests/system
+    remove_regex:
+      - packages/google-cloud-video-stitcher
+    tag_format: '{id}-v{version}'

scripts/configure_state_yaml/packages_to_onboard.yaml

@@ -95,6 +95,7 @@ packages_to_onboard: [
   "google-cloud-tpu",
   "google-cloud-trace",
   "google-cloud-translate",
+  "google-cloud-video-stitcher",
   "google-cloud-video-transcoder",
   "google-cloud-video-live-stream",
   "google-cloud-videointelligence",