Fix #6209: Add EDGE_TO_EDGE feature flag for edge-to-edge display support

[Neer-rn]

Explanation

Fixes #6209: This PR adds the EDGE_TO_EDGE feature flag that will be used to gate all edge-to-edge display changes behind a toggle.

On Android 15+ (API 35+), edge-to-edge is enforced by default and our app currently opts out using windowOptOutEdgeToEdgeEnforcement in values-v35/themes.xml. This opt-out is deprecated in SDK 36 and will stop working -- link: https://developer.android.com/about/versions/16/behavior-changes-16#edge-to-edge

So we need to properly handle window insets across all screens. This feature flag lets us gate those changes safely so we can roll back if something breaks.

Changes

• Added EDGE_TO_EDGE = 19 to the FeatureFlagId proto enum
• Added feature flag definition in feature_flags.textproto with default_is_enabled: false
• Added @EnableEdgeToEdge qualifier and default value in FeatureFlagConstants.kt
• Wired up the provider in FeatureFlagBindingModule.kt
• Wired up the map binding in FeatureFlagsMapBindingModule.kt
• Added forceEnableEdgeToEdge() in TestPlatformParameterModule.kt for tests
• Updated feature flag count to 16 in FeatureFlagsLoggerTest.kt

The flag is false by default and will be set to true once all screens are fixed in #5940 and #6208.

Full discussion and approach: #6196 and #5943

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