cmd/compile/internal/ir: add Type param to NewBasicLit

cmd/compile/internal/ir: add Type param to NewBasicLit

This CL adds an explicit Type parameter to NewBasicLit so that callers
can directly construct typed OLITERAL nodes.

Change-Id: I0ab50ac3d7ddb7adcc903633a62ac496921165e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/527096
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>