Add eye_height component to control player camera position

Currently in Bedrock, the player's FPS camera position is hardcoded and does not scale with the collision box. If you change the collision box height, the camera stays in the same place. This breaks immersion for addons that make the player giant or small. We need a component like "minecraft:eye_height" in player.json that lets addon creators control the real camera height independently. This would also work when the player crouches or swims, so the camera moves naturally with the body size. In Java Edition modders already have this freedom. Bedrock addon creators need it too. Use case examples: - Giant player looks down at small entities - Small player looks up at everything - Custom entities with correct camera perspective - More immersive shapeshifting addons