Add support for multiplane swapchain images in Wayland

Updates wsialloc and wsi::wayland::swapchain to support multiplane
image allocations.

Uses the custom allocator for allocations in Wayland image creation.

Change-Id: I1950b14b75711a76521bbf1967c3c835d006f8a8
Signed-off-by: Iason Paraskevopoulos <iason.paraskevopoulos@arm.com>
1 job for features_wayland in 1 minute and 23 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #9150668
build_vulkan_wsi_layer

00:01:23