Convert DrawerNavGroup to live code examples

[priyankakmEaton]

Fixes #5790

Changes proposed in this Pull Request:

-Convert images to live RN code (using react-native-web)

-Remove unused image assets

-Convert markdown code blocks to PrismJS code blocks

-Use PrismJS to highlight targeted lines in the code example blocks

-Include buttons to copy to clipboard and view full github source

Screenshots / Screen Recording (if applicable)

-

To Test:

-

Any specific feedback you are looking for?

-

[JeffGreiner-eaton]

looks like we need to use theme.colors for itemFontColor and titleColor...etc

Drawer nav group in dark theme