light theme will now use light navigation bar

[malmstein]

Task/Issue URL: https://app.asana.com/0/1157893581871903/1162814661890319

Description:
When the user selected Light Mode, the navigation bar was still showed in Dark. This PR fixes that.

Fixes: #695

Steps to test this PR:

1. Open current app in Google Play
2. Open Settings and select Light Theme
3. Check that Navigation bar is shown in Dark

Building this branch

1. Open app
2. Open Settings and select Light Theme
3. Check that Navigation bar is shown in Light

Screenshots:

Before	After

[marcosholgado]

This is great! However it doesn't work on Lollipop, how about removing the <item name="android:navigationBarColor">yourColorHere</item> from the specific themes and moving it to the top level one? That would make it work for all the versions.

[marcosholgado]

As discussed we can't change the navigation bar color prior 23 because we cannot change the icon colors so it would display white on white for APIs below 23. Looks like LG does something specific 🤷‍♂.

[malmstein]

Yeah! Some OEMs apparently did the right thing and tinted the color of the icons in the navigation bar pre v23. We can't rely on that for all devices, so for that reason we need to leave a dark navigation bar pre v23 even if the light theme is selected.