Test sparse input attachments in VkSubpassDescription

Test sparse input attachments in VkSubpassDescription

According to specification VkSubpassDescription::pInputAttachments can
handle more input attachments than maxPerStageDescriptorInputAttachments
as long as the number of used input attachments is below this limit.
The rest must have VK_ATTACHMENT_UNUSED flag set in pInputAttachments.

New tests:
dEQP-VK.renderpass.suballocation.attachment_sparse_filling.*
dEQP-VK.renderpass2.suballocation.attachment_sparse_filling.*

Components: Vulkan

VK-GL-CTS issue: 2034

Change-Id: I10bec67b6fd8eb722d81bd8ee7344475b7b0511a