Fix support for --headless.

[iagoCL]

Description

The main objective of this PR is to fix the --headless flag. Currently it does not work in the framework, due to not requesting a surface and swap chain.

This PR reworks HeadlessWindow to make it more similar to the other window classes. This will allow us to enable VK_EXT_headless_surface in HeadlessWindow::get_required_surface_extensions like the other windows types. Now we can remove the headless paramater from Instance::Instance and VulkanSample<>::create_instance simplifying the framework.

To keep the samples hello_world and hpp_hello_world as simple as possible, I did not add support for headless. Instead, an assert is run to ensure the are not enabling with headless in those samples.

General Checklist:

Please ensure the following points are checked:

• My code follows the coding style
• I have reviewed file licenses
• I have commented any added functions (in line with Doxygen)
• I have commented any code that could be hard to understand
• My changes do not add any new compiler warnings
• My changes do not add any new validation layer errors or warnings
• I have used existing framework/helper functions where possible
• My changes do not add any regressions
• I have tested every sample to ensure everything runs correctly
• This PR describes the scope and expected impact of the changes I am making

Note: The Samples CI runs a number of checks including:

• I have updated the header Copyright to reflect the current year (CI build will fail if Copyright is out of date)
• My changes build on Windows, Linux, macOS and Android. Otherwise I have documented any exceptions

If this PR contains framework changes:

• I did a full batch run using the batch command line argument to make sure all samples still work properly

Fixes #830
Fixes #314

[CLAassistant]

All committers have signed the CLA.

[SaschaWillems]

This crashes for me when trying to start any sample in headless mode.

The crash happens in getSurfaceSupportKHR in the vulkan hpp header and is coming from get_suitable_gpu in hpp_instance.cpp.

Callstack:

It works fine without headless.

System is Windows 11 with an NV RTX 4070 and recent Vulkan drivers. The K_EXT_headless_surface extension is supported.

I also have a switfshader ICD installed to test features not supported by my GPU, but the crash happens when calling getSurfaceSupportKHR for my discrete RTX 4070.