Add VK_EXT_multi_draw tests

Add VK_EXT_multi_draw tests

This commits adds a new test group with VK_EXT_multi_draw tests. The new
tests check the new API functions, the DrawIndex builtin and several
combinations of instance counts, strides, vertex offsets and number of
batched draw calls.

New tests:
dEQP-VK.draw.multi_draw.*

Affected tests:
dEQP-VK.info.device_mandatory_features

Components: Framework, Vulkan
VK-GL-CTS issue: 2897

Change-Id: Ifa6a92bd34c9f3509e82f6c346cc7eb5fd894bbc