nvk: Enable VK_KHR_pipeline_library
This is required for VK_EXT_graphics_pipeline_library and I somehow missed it. Also, enabling this extension enabled a few more tests which caught a bug in fast linking for which this MR has a fix.
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This is required for VK_EXT_graphics_pipeline_library and I somehow missed it. Also, enabling this extension enabled a few more tests which caught a bug in fast linking for which this MR has a fix.