fix: bottom navigation shifting={false} active pill display

[studioromeo]

Motivation

When the bottom nav has the attribute shifting={false} the pill shape is misformed on the active tabs. On clicking around this seems inconsistent.

This appears to be because the animated view is added / removed as the tab is focused causing the animation to not play or half play. Since it starts at 0.5 scaleX this appears to the user as a squashed pill shape. The intended animation is to expand out from the center.

This commit fixes this by ensuring the animation is always present and simply varies the outputRange of the animation depending on the focused state.

Related issue

https://github.com/callstack/react-native-paper/issues/4819

Test plan

Note: I had failures running the tests on main which i could not resolve so I've had to skip running the tests for this PR however I have run the other yarn checks. Apologies for this and I would appreciate if anyone could run the tests on this.

[callstack-bot]

Hey @studioromeo, thank you for your pull request 🤗. The documentation from this branch can be viewed here.