Refs #21467; embed-dashboard enhancements:

- Added get_dashboard_embed method to chart.py since we need the dashboard
  info as a python dict instead of a json string
- Made googlecharts-share div into a macro that is loaded by
  embed-dashboard
- Removed the inline styles which are loaded now from embed.css
- Added the same meta tags, title and doctype like in embed-chart
Refs #21467; added body font-size in order to lower the size of the embed type to match more of the text size of the chart