Export common utils/constants

We currently export the following:

• base components from ./src/components/base/* in ./index.js
• directives from from ./src/directives/*in ./index.js
• chart components from .src/components/charts/* in ./charts.js

In addition, we could also export utils/constants that could be useful in gitlab as well.

Examples include:

• chart colors
• UI utils such as hexToRgba, ...
• breakpoints.js: which is currently a duplicate from the gitlab repo and could be removed from gitlab entirely and imported from gitlab-ui instead
• ...