Add templates for Publish to BCR

Not sure if these are correct. I added a README so that our future
selves have some hope of figuring out what this is for. The metadata and
presubmit files I copied from our existing BCR entries.

https://github.com/bazelbuild/bazel-central-registry/blob/main/modules/boringssl/0.0.0-20240530-2db0eb3/presubmit.yml
https://github.com/bazelbuild/bazel-central-registry/blob/main/modules/boringssl/metadata.json

Change-Id: Ice8b7dee7360e44f77411db6fec8067a3204aa0b
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/71287
Commit-Queue: David Benjamin <davidben@google.com>
Auto-Submit: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
diff --git a/.bcr/README.md b/.bcr/README.md
new file mode 100644
index 0000000..2f619a8
--- /dev/null
+++ b/.bcr/README.md
@@ -0,0 +1,6 @@
+# Publish to BCR Configuration
+
+This directory contains configuration for the Publish to BCR app, which
+automates publishing releases to the Bazel Central Registry. See
+https://github.com/bazel-contrib/publish-to-bcr/tree/main/templates for
+details.
diff --git a/.bcr/config.yml b/.bcr/config.yml
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/.bcr/config.yml
diff --git a/.bcr/metadata.template.json b/.bcr/metadata.template.json
new file mode 100644
index 0000000..6d8f767
--- /dev/null
+++ b/.bcr/metadata.template.json
@@ -0,0 +1,25 @@
+{
+  "homepage": "https://boringssl.googlesource.com/boringssl/",
+  "maintainers": [
+    {
+      "email": "agl@google.com",
+      "github": "agl",
+      "name": "Adam Langley"
+    },
+    {
+      "email": "bbe@google.com",
+      "github": "bob-beck",
+      "name": "Bob Beck"
+    },
+    {
+      "email": "davidben@google.com",
+      "github": "davidben",
+      "name": "David Benjamin"
+    }
+  ],
+  "repository": [
+    "github:google/boringssl"
+  ],
+  "versions": [],
+  "yanked_versions": {}
+}
diff --git a/.bcr/presubmit.yml b/.bcr/presubmit.yml
new file mode 100644
index 0000000..f1253e9
--- /dev/null
+++ b/.bcr/presubmit.yml
@@ -0,0 +1,33 @@
+build_targets: &build_targets
+  - "@boringssl//:crypto"
+  - "@boringssl//:ssl"
+
+matrix:
+  platform:
+    - centos7_java11_devtoolset10
+    - debian11
+    - ubuntu2204
+    - windows
+  bazel: [6.x, 7.x]
+tasks:
+  verify_targets:
+    name: Verify build targets
+    platform: ${{ platform }}
+    bazel: ${{ bazel }}
+    build_targets: *build_targets
+  # Work around https://github.com/bazelbuild/bazel/issues/10472
+  verify_targets_on_macos:
+    name: Verify build targets on macOS
+    platform: macos
+    bazel: ${{ bazel }}
+    build_targets: *build_targets
+    build_flags:
+      - '--cxxopt=-std=c++14'
+      - '--sandbox_block_path=/usr/local'
+  run_test_module:
+    name: Run test module
+    platform: ${{ platform }}
+    bazel: ${{ bazel }}
+    module_path: util/bazel-example
+    build_targets:
+      - //...
diff --git a/.bcr/source.template.json b/.bcr/source.template.json
new file mode 100644
index 0000000..2037471
--- /dev/null
+++ b/.bcr/source.template.json
@@ -0,0 +1,5 @@
+{
+  "integrity": "",
+  "strip_prefix": "{REPO}-{VERSION}",
+  "url": "https://github.com/{OWNER}/{REPO}/releases/download/{TAG}/{REPO}-{TAG}.tar.gz"
+}