`macos_application` fails to run if name ends with `.app`

Given a `macos_application` with a `name = "Foo.app"`, when running `bazel run //:Foo.app` it will fail.

I ran the script it creates to run the app and noticed:

```
[1] 90093 killed ./bazel-bin/Foo.app
```

It looks like `.app` gets handled differently by the OS when used as an extension.

Start by reproducing the issue with a macos_application named "Foo.app" and run `bazel run //:Foo.app`; inspect the generated script and the handling of the `.app` suffix. Done means the generated launcher runs an application whose name already ends in `.app` without being killed by macOS.

Written by the indexing model from the issue text.