vulkan/overlay: drop dependency on validation layer headers

v2: reimplement layer chain info getters (Eric)

v3: make it compile.. (Lionel)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
25 jobs for !383 with wip/djdeath/vulkan-overlay-dispatch-fix in 48 seconds (queued for 1 minute and 35 seconds)
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