Bind FloatingActionButton variants: Small/Large/Extended

[jonathanpeppers]

Only the base FloatingActionButton is wrapped. Material 3 1.4 ships size variants (Small, Large) and an extended (icon + label) variant — none are bindable today.

Missing composables (bindable in Xamarin.AndroidX.Compose.Material3 1.4.0.3)

Composable	Kt class	Notes
SmallFloatingActionButton	FloatingActionButtonKt	SmallFloatingActionButton-X-z6DiA — same shape as existing FAB
LargeFloatingActionButton	FloatingActionButtonKt	LargeFloatingActionButton-X-z6DiA — same shape
ExtendedFloatingActionButton (single content)	FloatingActionButtonKt	ExtendedFloatingActionButton-X-z6DiA — Function3<RowScope, …> content slot
ExtendedFloatingActionButton (icon + text + expanded)	FloatingActionButtonKt	ExtendedFloatingActionButton-ElI5-7k — multi-slot (icon, text, expanded:Boolean)

The M3 Expressive variants (MediumFloatingActionButton, FloatingActionButtonMenu, ToggleFloatingActionButton) are tracked separately in #103 — they need a newer Material3 NuGet.

Approach

Same as the existing FloatingActionButton — all four are hash-mangled (FloatingActionButton-X-z6DiA) because of Color / Dp inline-class parameters, so they need [ComposeBridge] partials + declarative [ComposeDefaults] enums.

The single-content ExtendedFloatingActionButton can use [ComposeFacade(Scope = "Row")] (same as Button/IconButton content). The icon/text overload has two slot lambdas — model the same way AlertDialog exposes named slot properties cleared from the defaults bitmask per call.

Tracking

Long-term, dotnet/java-interop#1440 lets the bridges collapse into the generated bindings.