Add GraphicsShapes demo and integration tests for PolygonShape and MorphPolygonShape

Adds a comprehensive interactive demo in ui-demos for PolygonShape and MorphPolygonShape, along with integration tests in foundation verifying multi-size resolution and continuous shape morphing.

Test: ./gradlew :compose:foundation:foundation:connectedAndroidTest -Pandroid.testInstrumentationRunnerArguments.class=androidx.compose.foundation.shape.PolygonShapeIntegrationTest
Fixes: 378826438
Change-Id: I0465d3bb569f3bd85e8a671f62e8c5cf581880fd