Maintenance1\1.1 compatibility

The Maintenance1 appendix discusses that `VK_FORMAT_FEATURE_TRANSFER_*_BIT_KHR` was added to allow indicate support for formats that can do transfer **only**.

But it is not clear, that any other format feature implies that `VK_FORMAT_FEATURE_TRANSFER_*_BIT_KHR` should be set. This leads to odd situation that some format may be supported for transfer in core, but not with extension enabled.

I think that is not backwards-compatible, as we established in #638.

Also:

> Note:
If no format feature flags are supported, the format itself is not supported, and images of that format cannot be created.

It is not clear from this if `0` is always returned for unsupported formats, or if enumerants for non-enabled extensions may also be returned.

PS:
Reference to `VK_FORMAT_FEATURE_TRANSFER_*_BIT_KHR` in `vkCreateImage` seems to be missing in VU section. And it is unnecessarily in many commands VUs. What am I missing?

Start with the Maintenance1 appendix and the vkCreateImage and other command VU sections referenced in the issue, then compare the compatibility discussion in #638. Clarify whether core transfer support implies the KHR flags, how unsupported formats and non-enabled extension enumerants are reported, and which VUs should reference the flags; done means the specification answers these points consistently.

Written by the indexing model from the issue text.