Implement minimal Jest setup

This is part of https://gitlab.com/gitlab-org/gitlab-ce/issues/52483.

merge in minimal Jest setup (without tests)

• Jest configuration file
• new spec/frontend/ directory with dummy test
• fail long running tests (https://gitlab.com/gitlab-org/gitlab-ce/issues/44174)
• add to .gitlab-ci.yml
• documentation on how to run the Jest suite