Improve visuals of language bar on projects

What does this MR do?

Builds on top of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19480

Added minimum width for small percentage languages, made measures consistent with grid as set by design.GitLab.com which improves target area for hover.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

• Wasn't compliant with https://design.gitlab.com/layout/grid
• Target area needed to be a bit bigger for hover tooltips
• Very small percentage languages were almost invisible before
• Improves distinction between 2 languages, by adding a minor margin/whitespace

Screenshots (if relevant)

Old:

New:

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conforms to the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19480