Universe: remove Bazel files

The reasoning is fairly simple: nobody is actively working on
integrating with Bazel and there are no plans/capacity to do so. It
might be because Bazel is quite complex, and it's hard to set up it in a
way we need it to be. Moreover, it's blocking other efforts like this
one for example: adeira/universe#2154 (Yarn 2).

Note: this doesn't mean that there is no need for something like Bazel.
However, it doesn't have to be Bazel (preferably something simpler that
does the job well enough).

adeira-source-id: 4806cd43ff2ef8ca082d7b51e6c9da493e55f946

.npmignore

@@ -1,4 +1,2 @@
 __tests__
 test-helpers
-BUILD.bazel
-BUILD