Re-add nav_settings Customizer section

[cjg89]

Description

See title. We currently remove the section in the Customizer to reduce clutter, but as of v1.2.0, we do utilize the Main Site nav menu on single Statement posts.

https://github.com/UCF/Today-Child-Theme/blob/master/includes/config.php#L40-L54

Why it's Important

The Main Site nav is utilized in this theme as of v1.2.0, so we should display the relevant Customizer settings for it.

Alternatives

n/a

Possible Implementation

Update today_define_customizer_sections() to remove the $wp_customize->remove_section( UCFWP_THEME_CUSTOMIZER_PREFIX . 'nav_settings' ) call.

Additional context

n/a