feat(bottom-tabs): per-tab icon size & active-indicator sizing on the native tab bar

[stachbial]

What

Bottom-tab icon sizing options, on the native bar:

• tabBarIconSize (dp) — per-tab icon size. On the custom (JS) bar it sizes the icon on all platforms; on the native bar it maps to react-native-screens' drawableIconSize — the bar boxes to the largest size across tabs and insets smaller ones (Android only). Unset uses the default.
• tabBarActiveIndicatorWidth / tabBarActiveIndicatorHeight (dp) — bar-wide active-indicator size, taken from the focused tab. Native bar only; unset auto-scales to wrap the icon box.

Android drawable tinting on the native bar is driven by image's tinted (no tintingMode in the public API) — tinted: false keeps the drawable's own colors.

Also fixes tabBarIconStyle's type (TextStyle → ViewStyle) — it styles the icon container View.

Changes since review

• Rebased onto PlatformIcon.
• tabBarIconSize is no longer restricted to Android on the custom implementation — it is plain RN layout and works on iOS too. It stays Android-only on the native implementation, where it maps to drawableIconSize.
• Non-square image sizing moved out to aspectRatio (feat(elements): add aspectRatio to image icons #13194); this PR is stacked on it.

Depends on

• feat(elements): add aspectRatio to image icons #13194 (icon aspectRatio) and feat(tabs): custom drawable/symbol tab-bar icons — tinted, per-tab size, indicator sizing, iOS fallback software-mansion/react-native-screens#4209 (native Android support). Stays a draft until creating simple stacknavigator using createStackNavigator #4209 publishes — the cross-repo tinted on PlatformIconAndroid isn't in the released screens types yet.

Test plan

Native bottom tab navigator on Android, with react-native-screens from #4209:

• tabBarIconSize on one screen scales that tab's icon; others stay default.
• tabBarActiveIndicatorWidth / tabBarActiveIndicatorHeight in screenOptions reshape the indicator.
• tinted: false on a multicolor drawable keeps its colors as a tab icon.
• On the custom (JS) bar, tabBarIconSize scales the icon on iOS and Android.