Add list of Vulkan extensions to info output

[jacobv-nvidia]

Currently, in order to get information about which Vulkan extensions are requested in a capture, the primary workflow is to use the gfxrecon-convert utility to obtain the JSON output, and then separately inspect each instance/device CreateInfo structure. This can become quite inconvenient, especially for larger capture files.

This PR resolves the issue by having the gfxrecon-info tool perform this collection automatically and include the list of requested Vulkan extensions as part of its normal output.

An example of the additional gfxrecon-info output:

...
	Target API version:

Extension info:
        Instance extensions:
                VK_KHR_get_physical_device_properties2
                VK_KHR_surface
                VK_KHR_win32_surface
                VK_KHR_portability_enumeration
        Device extensions:
                VK_KHR_portability_subset
                VK_KHR_swapchain

Physical device info:
...