Add a .bazelrc file. (#10)

This file helps standardize the invocation of bazel for this repository. The file was copied from https://github.com/material-components/material-components-ios/blob/24601d8b08344ba1da9d76479134c6061c30ff97/.bazelrc

This is part of https://github.com/material-components/material-components-ios/issues/9363

Tested manually by running:

```
bazel test //...
```

And verifying that it succeeds. Note that we do not need to pass `--apple_platform_type=ios` as we did with #9

.bazelrc

@@ -0,0 +1,24 @@
+# Copyright 2020-present The Material Foundation Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Common flags for all builds
+build --verbose_failures  # Print the full command line for commands that failed.
+build --test_output=errors  # Prints log file output to the console on failure.
+
+# Platform-specific flags
+build --apple_platform_type=ios  # Build for iOS by default.
+
+# Swift-specific features: https://github.com/bazelbuild/rules_swift/blob/master/swift/internal/features.bzl
+build --features=swift.enable_batch_mode  # Intended to speed up non-incremental non-WMO builds.
+build --features=swift.use_global_module_cache  # Use the same global Clang module as ObjC targets.