Push Protobufs to Buf Schema Registry

This registry generates us documentation. I believe it also allows us to
avoid copying around protobuf files, which we currently need to do for
each SDK (e.g. https://github.com/crossplane/function-sdk-go/tree/main/proto).

Signed-off-by: Nic Cope <nicc@rk0n.org>

.github/workflows/ci.yml

@@ -451,3 +451,35 @@ jobs:
         with:
           name: artifacts
           path: ./out/artifacts
+
+
+  protobuf-schemas:
+    runs-on: ubuntu-22.04
+    needs: detect-noop
+    if: needs.detect-noop.outputs.noop != 'true'
+
+    steps:
+
+      - name: Checkout
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
+
+      - name: Setup Buf
+        uses: bufbuild/buf-setup-action@v1
+
+      - name: Lint Protocol Buffers
+        uses: bufbuild/buf-lint-action@v1
+        with:
+          input: apis
+
+      - name: Detect Breaking Changes in Protocol Buffers
+        uses: bufbuild/buf-breaking-action@v1
+        with:
+          input: apis
+          against: "https://github.com/${GITHUB_REPOSITORY}.git#branch=master,subdir=apis"
+
+      - name: Push Protocol Buffers to Buf Schema Registry
+        if: github.ref == 'refs/heads/master'
+        uses: bufbuild/buf-push-action@v1
+        with:
+          input: apis
+          buf_token: ${{ secrets.BUF_TOKEN }}

apis/buf.yaml

@@ -0,0 +1,10 @@
+version: v1
+name: buf.build/crossplane/crossplane
+deps:
+- buf.build/protocolbuffers/wellknowntypes:v24.4
+breaking:
+  use:
+    - FILE
+lint:
+  use:
+    - DEFAULT