Improve tests checking sign extension with images

Improve tests checking sign extension with images

Changes the existing sign extension operand tests:

* Operands are now checked independently on read and write operations.
* 64-bit formats are also checked when supported.

Parts of the framework have been modified to improve 64-bit format
support and to properly check 64-bit output pixel values.

This commit replaces the dEQP-VK.image.extend_operands_spirv1p4 test
group with new variants.

New tests and removed tests:
dEQP-VK.image.extend_operands_spirv1p4.*

Components: Framework, Vulkan
VK-GL-CTS issue: 2885

Change-Id: Ia6b3c06b81347d7b007a1adb49a80b04dda5db83