Add enough BUILD files to make it possible to
`bazel build packages/core/test`
Also re-format BUILD.bazel files with Buildifier.
Add a CI lint check that they stay formatted.
PR Close#20768
- update to TypeScript 2.5
- point the 2.4 typings test at the previous typescript version, so we
don't break it accidentally
- widen the peerDeps from Angular packages that depend on TypeScript
- update to latest TypeScript 2.5 compatible Bazel rules
- move .bazelrc to tools/bazel.rc per https://docs.bazel.build/versions/master/best-practices.html#bazelrc
PR Close#20175