Reworking Health's design

See #178

General

• Top-align all listboxes
• Sub-views should have the view title in the headerbar
• Listboxes should have clamp values closer to PreferencesPage (to avoid awkward wide rows with lots of vertical but no horizontal whitepsace)
• New About dialog

Welcome page

• Can't go to the second page unless you change every value, including metric/imperial
• Should probably be a modal above the actual main window
• Left aligned text should be centered, subtitles should be regular font size
• Google list button should at least have a external link icon, and maybe include a subtitle explaining what will happen. Maybe make it a pill button while there's only one?

Main view:

• Remove "disable current plugin" from menus
• Show primary menu only on main page, not subpages
• Drop "for you" title
• Use new widgets (adwtoolbarview, navigationview, etc.)
• For listbox items display data point with a more prominent style on the left, and add illustrations / visualizations on the right
• Add arrows on the right in listbox rows
• Unlink listbox rows
• Change "add" button into two floating circular buttons in the bottom right

Add dialog:

• Use separate dialogs for weight and activity
• Experiment with dropping extra labels in date chooser row, and having day/month/year inline next to each other
• Make the most important entry more prominent, by splitting up the list (e.g. minutes + distance for walking, minutes only for football). For example, 3 sections:
  • date
  • activity + minutes + distance
  • calories
  • maybe drop heart rate?
• "Add" button instead of "Save"

Subpages:

• Maybe drop border around charts? At least at bottom and sides, where it's not separated from anything else
• Maybe drop passive calories?
• Content in tooltips should be centered in the container