Allow "larger text" to be applicable to navigation bar text

Allow "larger text" to be applicable to page titles. This involves enlarging page titles and button text within navigation bars by a fraction for accessibility. For reference see any Apple app.

Settings:

Start by locating the existing "larger text" accessibility setting and the navigation bar title and button rendering entry points. Verify how the setting currently affects page content, then confirm that navigation bar titles and button text enlarge by a fraction when enabled, with unaffected sizing when it is disabled.

Written by the indexing model from the issue text.