Add multisample support for ShadingRatePattern.

[jorgeag-google]

The fourth of a series of CL that integrates the commits from: https://github.com/bjoeris/bigwheels/tree/experimental-foveation into BW main's branch. The series has 4 CL, this is the last one that integrates the following commit

• Add multisample support for ShadingRatePattern.

Beside the foveation sample app, it also adds the following changes in BW infra:

• ShadingRate’s class add sample count properties, that queries from device
• Modifies gfx View classes to get the sample count from images
• Image class get samples count from createinfo struct
• ShadingRates unit test get modified to account for this changes