In-memory data visualizations of vector types were using indices
for displaying vector elements. For non-memory data, we use
.x .y .z .w for vectors <= 4 elements.

Mirror this for in-memory data.

Bug: b/148401179
Change-Id: Ib2e8e2019ab274dfae2d6e18978f41c721c800a1
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/45609
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Tested-by: Ben Clayton <bclayton@google.com>