Add input attachment support for VK_FORMAT_R5G6B5_UNORM_PACK16
Add input attachment support for VK_FORMAT_R5G6B5_UNORM_PACK16

Bug: b/131171141
Test: dEQP-VK.*r5g6b5*
Change-Id: I92058fb4ecc327dd1db67b47c327aa0e5d149135
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/30532
Tested-by: Chris Forbes <c3279c50043e18e9442c1ae071cafa0e7a4ca967@google.com>
Presubmit-Ready: Chris Forbes <c3279c50043e18e9442c1ae071cafa0e7a4ca967@google.com>
Reviewed-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Kokoro-Presubmit: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader