Bazel builds

• We use Bazelisk, which automatically picks the correct version of Bazel for a branch
• We don’t yet generate files in bazel - we use external scripts (for now)
• We strip bazel files from external dependencies, so we don’t confuse gazelle

• By default the command doesn’t allow tests to use data. So we need to use or similar. We add to stop gazelle from removing it. doesn’t make it easy to access files in a parent directory, so we’ll have to clean up some of the test / package structure.