feat: add three button navbar

[alexisdelage]

Description

Add a feature to test with a 3-button system navigation bar.
Re-use the Pixel5 config, but with the optional parameter for displaying the 3-button navbar instead of the default gestures-navigation.

Why

Being able to test an app with a large bottom safe-area, especially given the fact that Scaffold does not always add the bottom safe area on our screens.

[alexisdelage]

Score pana : 160/160

[T-moz]

@alexisdelage if you add the tree buttons. You should add the all the options available on pixel 9:

[alexisdelage]

@alexisdelage if you add the tree buttons. You should add the all the options available on pixel 9

@T-moz Do you have an example of what 2-buttons look like? I never saw this option before. Also not sure if it is useful, since the main goal here is to anticipate bigger bottom safe-area (I doubt 2-button navigation bar would be bigger in height than 3-button)