Allow switching to wasmtime through the GOWASIRUNTIME variable. This
will allow builders to run the wasip1 standard library tests against
the wasmtime WASI runtime.
For #59583
Change-Id: I4d5200df7bb27b66e041f00e89d4c2e585f5da7c
Reviewed-on: https://go-review.googlesource.com/c/go/+/485615 Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Bypass: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>
Run-TryBot: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com> Reviewed-by: Cherry Mui <cherryyz@google.com>