Add bcr setup for gazelle (#519)

.bcr/gazelle/metadata.template.json

@@ -0,0 +1,15 @@
+{
+  "homepage": "https://github.com/bazelbuild/bazel-skylib",
+  "maintainers": [
+    {
+      "email": "ilist@google.com",
+      "github": "comius",
+      "name": "Ivo Ristovski List"
+    }
+  ],
+  "versions": [],
+  "yanked_versions": {},
+  "repository": [
+    "github:bazelbuild/bazel-skylib"
+  ]
+}

.bcr/gazelle/presubmit.yml

@@ -0,0 +1,17 @@
+matrix:
+  platform:
+  - centos7
+  - debian10
+  - macos
+  - ubuntu2004
+  - windows
+  bazel:
+  - 7.x
+  - 6.x
+tasks:
+  verify_build_targets:
+    name: "Verify build targets"
+    platform: ${{ platform }}
+    bazel: ${{ bazel }}
+    build_targets:
+    - "@bazel_skylib_gazelle_plugin//..."

.bcr/gazelle/source.template.json

@@ -0,0 +1,5 @@
+{
+  "integrity": "",
+  "strip_prefix": "",
+  "url": "https://github.com/{OWNER}/{REPO}/releases/download/{TAG}/bazel-skylib-gazelle-plugin-{TAG}.tar.gz"
+}