Closes #17091

- Simpler main nav on all pages
- Back to purple masthead on homepage instead of dark graphite
- Active link styles on the main nav
- Cleaned up sidebar nav
- New docs layout name
- Homepage copy edits
- Updated bright purple docs color

move compilting to build-tools, rewrite some grunt stuff, add local docs with jekyll section based on readme's more detailed walkthrough

- drop the index pages save for examples
- comment out the extend section for now
- fix up spacing fix on team list

- Replaces manual use of .bd-callout with {% callout [type] %}
- Rearranged some callouts for proximity to others
- Turned long lists of callouts--like those on tooltips, plugings, etc--into a list because holy shit that's overwhelming