Cast invocation ID correctly in allequal tests

Cast invocation ID correctly in allequal tests

The gl_SubgroupInvocationID was not being cast to the appropriate type
in the vote.allequal tests, so every type was testing the uint version.
The ARB extension tests worked around this by specifically casting to
bool because there is no uint version in the ARB extension. This version
casts the invocation ID to the appropriate type for the test. This part
of the test is skipped for boolean types because there may not be an
invocation with ID 0, so the results may all be equal ( == true),
contrary to the test's expectation.

Component: Vulkan
VK-GL-CTS issue: 1845
Affects: dEQP-VK.subgroups.vote.*

Change-Id: I98a01fa2398cc4cdc18125af2cc64f59a5d559ca