Rename every BUILD file to BUILD.bazel (#170)

This should improve compatibility with MacOS and its case-insensitive
filesystem.

Fixes #169.

.github/license-check/license-config.json

@@ -5,7 +5,7 @@
       "**/*.py",
       "**/*.sh",
       "**/*.yml",
-      "**/BUILD",
+      "**/BUILD.bazel",
       "tools/bin/au-docs-serve",
       "tools/bin/buildifier",
       "tools/bin/clang-format",
@@ -25,7 +25,7 @@
   },
   {
     "include": [
-      "third_party/bazelisk/BUILD"
+      "third_party/bazelisk/BUILD.bazel"
     ],
     "license": "./.github/license-check/header-apache2-hashtag.txt"
   },

WORKSPACE

@@ -127,7 +127,7 @@ http_archive(
 http_archive(
     name = "nholthaus_units",
     add_prefix = "nholthaus_units",
-    build_file = "@//third_party/nholthaus_units:BUILD",
+    build_file = "@//third_party/nholthaus_units:BUILD.bazel",
     sha256 = "b1f3c1dd11afa2710a179563845ce79f13ebf0c8c090d6aa68465b18bd8bd5fc",
     strip_prefix = "units-2.3.3/include/",
     url = "https://github.com/nholthaus/units/archive/refs/tags/v2.3.3.tar.gz",