Option to list all properties/features

[JuanDiegoMontoya]

The current drop-downs let you search for properties/features from different versions separately.

If you don't know when a specific feature was introduced, it can be quite cumbersome to click through each of these options and search for it (or alternatively, find the feature in the spec to see when it was introduced).

It would be nice if there was an "All Core" option that listed all properties/features in core Vulkan, and perhaps an "All Core + Extensions" option to show everything, including extensions.