Add a custom allocator(like polymorphic_allocator) when some RAII methods return std containers.

Thank you for open-sourcing this modern C++ Vulkan wrapper library. Our project is currently trying to use `vulkan-hpp`, but I noticed that some methods which return std containers use `std::allocator`, as shown below.

```cpp
// wrapper function for command vkEnumerateInstanceExtensionProperties, see
// https://registry.khronos.org/vulkan/specs/latest/man/html/vkEnumerateInstanceExtensionProperties.html
VULKAN_HPP_NODISCARD typename ResultValueType>::type
enumerateInstanceExtensionProperties( Optional layerName VULKAN_HPP_DEFAULT_ASSIGNMENT( nullptr ) ) const;

// wrapper function for command vkEnumerateInstanceLayerProperties, see
// https://registry.khronos.org/vulkan/specs/latest/man/html/vkEnumerateInstanceLayerProperties.html
VULKAN_HPP_NODISCARD typename ResultValueType>::type enumerateInstanceLayerProperties() const;
```

This means that if I need to store this data, I have to copy it into our `pmr` containers to keep the types consistent. It would be ideal if a macro could be added to enable or disable a custom allocator. My personal idea is as follows:

```cpp
template
using VKHppStdContainerAllocator =
#if defined(VULKAN_HPP_USE_PMR_ALLOCATOR)
std::polymorphic_allocator;
#else
std::allocator;
#endif

// wrapper function for command vkEnumerateInstanceExtensionProperties, see
// https://registry.khronos.org/vulkan/specs/latest/man/html/vkEnumerateInstanceExtensionProperties.html
// add allocator
VULKAN_HPP_NODISCARD typename ResultValueType>>::type
enumerateInstanceExtensionProperties( Optional layerName VULKAN_HPP_DEFAULT_ASSIGNMENT( nullptr ) ) const;

// wrapper function for command vkEnumerateInstanceLayerProperties, see
// https://registry.khronos.org/vulkan/specs/latest/man/html/vkEnumerateInstanceLayerProperties.html
VULKAN_HPP_NODISCARD typename ResultValueType>>::type enumerateInstanceLayerProperties() const;
```
PS. If this issue is acceptable and this repository welcomes PRs, I would be happy to try contributing this part of the code.

Start with the wrapper declarations for enumerateInstanceExtensionProperties and enumerateInstanceLayerProperties shown in the issue, then trace how their std::vector return types are generated. Define what allocator selection must cover and verify that PMR-enabled returns use the custom allocator while the default behavior remains unchanged.

Written by the indexing model from the issue text.