Implement the VK_KHR_swapchain_mutable_format device extension in the vulkan loader

Add an implementation for the VK_KHR_swapchain_mutable_format extension.

Test: Stepped through changes in debugger
Test: Ran sample app with VVL which used the extension
Test: Ran dEQP-VK.image.swapchain_mutable.android.* dEQP tests
Flag: com.android.graphics.libvulkan.flags.swapchain_mutable_format_ext
Bug: 341978292
Change-Id: Ib0e5b9f750cd5a94ab65419542898db207716fcc