[go] Support 'go.work' file and resolve shared deps relative to work path (#9708)

This PR fixes a few issues related to `vc dev`.

1. Create a default `go.work` file in the cache dir when building the `vercel-dev-server-go` executable
2. Copy the existing `go.mod` file into the cache dir and update any "replace" relative paths
3. Split the "build" logic into separate functions for the legacy "main" package build and the `go.mod` build

Additionally, it fixes:

1. `vc build`: pass in `build.env` from `vercel.json`
2. Fix several tests to work with `vc dev` and `vc build`

Linear: https://linear.app/vercel/issue/VCCLI-638/vc-dev-go-builder-cant-resolve-workspace-dependencies

The user that reported the issue has tested this build and seems to fix their use case: https://github.com/vercel/vercel/issues/9393#issuecomment-1490726785.

packages/cli/test/dev/fixtures/go-work-with-shared/api/index.go

@@ -0,0 +1,12 @@
+package handler
+
+import (
+	"fmt"
+	"net/http"
+	"go-work-with-shared/mylib"
+)
+
+// Handler function
+func Handler(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintf(w, mylib.Say("hello"))
+}