feat(cloudflare): experimental config redirection support

[pi0]

Nitro has introduced an experimental (opt-in) way to generate/extend wrangler.toml for cloudflare deployments (#2353, #2355).

The end goal is to leverage Cloudflare platform features such as Node compat v2 (hybrid) and Async Context with zero-config and ensure we can reliably enable these features.

However, overwriting the user config is not ideal or recommended.

Thanks to the huge huge efforts and collab with the Cloudflare team and @petebacondarwin, a new solution (~> cloudflare/workers-sdk#7442) is coming to allow frameworks like Nitro to generate a merged wrangler.toml in dist and config that redirects/points wrangler CLI and pages CI to it.

This PR is to experiment this new feature e2e from both sides.

Remarks

• As before, this feature is only effective when there is extra cloudflare.wrangler: {} config is provided
• New mode is opt-in via EXPERIMENTAL_WRANGLER_CONFIG env variable
• Old method is to be removed as soon as feat: add support for redirecting Wrangler to a generated config when running deploy commands cloudflare/workers-sdk#7442 is globally availble
• We currently resolve configs from rootDir, it might need to be changed to cwd() later for monorepo support (pending more tests)
• New support is added for reading wrangler.json from user
• Merging strategy is to be improved, however we always respect explicit user config in wrangler.toml|json over

Local testing

• pnpm build --stub
• EXPERIMENTAL_WRANGLER_CONFIG=1 p nitro build playground --preset cloudflare_pages

ℹ Generated playground/dist/_routes.json                                                                                        
ℹ Generated playground/dist/_headers                                                                                             
ℹ Generated playground/dist/_redirects                                                                                           
ℹ Generated playground/.wrangler/deploy/config.json                                                                              
ℹ Generated playground/dist/_worker.js/wrangler.json 

.wrangler/deploy/config.json:

{"configPath":"../../dist/_worker.js/wrangler.json"}

wrangler.toml (user)

compatibility_flags = [ "nodejs_als" ]
name = "nitro-test"
compatibility_date = "2024-09-19"

[assets]
directory = "./.output/public/"
binding = "ASSETS"

[durable_objects]
[[durable_objects.bindings]]
name = "$DurableObject"
class_name = "$DurableObject"

[[migrations]]
tag = "v1"
new_classes = [ "$DurableObject" ]

dist/_worker.js/wrangler.json

{
  "compatibility_flags": [
    "nodejs_als",
    "nodejs_als"
  ],
  "name": "nitro-test",
  "compatibility_date": "2024-09-19",
  "assets": {
    "directory": "./.output/public/",
    "binding": "ASSETS"
  },
  "durable_objects": {
    "bindings": [
      {
        "name": "$DurableObject",
        "class_name": "$DurableObject"
      }
    ]
  },
  "migrations": [
    {
      "tag": "v1",
      "new_classes": [
        "$DurableObject"
      ]
    }
  ]
}