Add support for new api "vulkanbase" (KhronosGroup#2323)

* Add support for api "vulkanbase"

* Merge internal APIs before processing

After loading the XML, merge internal API blocks into the public ones
so that we don't litter the vulkan and vulkan sc headers with
Base/Compute/Graphics version notations.

* Modify algorithm to merge internal features into public ones.

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Co-authored-by: Daniel Koch <[email protected]>

C++Module: Fixing import std on enum header and using `export import …

…std` when appropriate (KhronosGroup#2283)

* fix std import on enum header

* remove duplicate contents in cppm

* moved dynamic enabling of std module into macro header

* do not automatically enable import std

* automatic opt-out approach for export import std

* added opt-out option VULKAN_HPP_NO_STD_MODULE

* add VULKAN_HPP_NO_STD_MODULE to CI workflows

* added VULKAN_HPP_NO_STD_MODULE flag to the readme

* set VULKAN_HPP_NO_STD_MODULE to OFF by default

* added import_std exclusion to ubuntu-ext CI

Update Vulkan-Headers to v1.4.326 (KhronosGroup#2267)

Co-authored-by: GitHub <[email protected]>

Minor code cleanup (KhronosGroup#2253)