[go] Go builder improvements (#9576)

This PR fixes a handful of Go builder issues all related to the selected Golang version being used to build the function:

- `go.mod` version ignored for `vc build` and `vc dev`, uses system `PATH` version only
- `vc dev` fails if `go.mod` does not exist
- If the analyze bin doesn’t exist, downloads golang into `.vercel/cache/golang` instead of a global shared dir
- When running `vc dev`, doesn’t reuse go build code/common settings
- go tidy fails when `go.mod` set to 1.19 or 1.20, but 1.18 or older is installed
- `vc build` builds wrong arch on Apple Silicon/arm64
- `vc build` on Windows doesn't properly resolve "builds" in `vercel.json` due to posix separator issue
- `vc build` on Windows fails with `package <pkg/name> is not in GOROOT` due to posix separator issue
- Removed `actions/setup-go` from all test workflows

I added a test that tests the `go tidy` issue.

packages/cli/src/commands/build.ts

@@ -1,7 +1,7 @@
 import fs from 'fs-extra';
 import chalk from 'chalk';
 import dotenv from 'dotenv';
-import { join, normalize, relative, resolve } from 'path';
+import { join, normalize, relative, resolve, sep } from 'path';
 import {
   getDiscontinuedNodeVersions,
   normalizePath,
@@ -712,7 +712,9 @@ function expandBuild(files: string[], build: Builder): Builder[] {
     });
   }
 
-  let src = normalize(build.src || '**');
+  let src = normalize(build.src || '**')
+    .split(sep)
+    .join('/');
   if (src === '.' || src === './') {
     throw new NowBuildError({
       code: `invalid_build_specification`,