Rename Intermediate::emplace() to move()

Rename Intermediate::emplace() to move()

Since we're essentially assigning from one rvalue to another, move()
seems to describe the intent better and even matches
register-to-register move instructions.

Bug b/128539387

Change-Id: I409b3ede9578a100f25ea92e61f7492a38341ca4
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/26869
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>