MOVE Design System: typography

[candu]

Description
After dev/design pairing with @shinechaudhuri , we've laid out the general elements of our design system.

This task implements the typography part of that.

Acceptance Criteria

• selectors defined for header levels and other typography classes;
• use header tags <h*> as appropriate for different headings throughout the application;
• remove letter-spacing from buttons, tabs, other UI elements;
• ensure all date formatting is using the same functions (maybe even define components for these, for readability?);
• dot separators.

Additional Notes
This will probably also mean adding a set of colors.

We have #313 as a separate task for reports - we don't need to worry about those here.