Let VVL help debug `VK_ERROR_FEATURE_NOT_PRESENT`?

This request is probably the inverse of #335. In an app that I'm trying to capture in RenderDoc, that I'm not yet entirely familiar with, `VK_ERROR_FEATURE_NOT_PRESENT` is raised back to the app. I'm unsure which feature of the possibly large `pNext` chain is the root cause of this.

Since RenderDoc inserts the VVL between the app and its own capture layer (validated with `VK_LOADER_DEBUG=layer`, nice!), I'm also not sure if it's the app suddenly requesting something unsupported by the device (while it did work outside RenderDoc), the RenderDoc capture layer requesting something unsupported (wouldn't be caught by the VVL if it sits between the capture layer and the app, of course), or RenderDoc returning this error to this app if it turns out to be hiding a certain feature from the app.

#337 seems to remove _pre_ validation to address #335, while I might be interested in (autogenerated?) _post_ "validation" to compare and pretty-print the mismatching feature(s) whenever `vkCreateDevice()` returned `VK_ERROR_FEATURE_NOT_PRESENT`. Is that something that is in scope or even feasible for the VVL? Thanks!