Add tests for VK_EXT_shader_subgroup_ballot

Add tests for VK_EXT_shader_subgroup_ballot

Add tests for read*InvocationsARB() and other defines added by
VK_EXT_shader_subgroup_ballot extension.

Tests are based on the existing ones for subgroup's ballot feature but
adapted to the extension.

These tests don't check the gl_SubGroup*MaskARB variables, they will
be added in other CL.

New tests:

dEQP-VK.subgroups.ballot.ext_shader_subgroup_ballot.*
dEQP-VK.subgroups.ballot_broadcast.ext_shader_subgroup_ballot.*

Components: Vulkan
VK-GL-CTS issue: 1692

Change-Id: Ic694c371245ebde5883f507c26cd6caead15ed87