Improve Netlify bundled configuration

- Add support for using `netlify dev`. This is important if you want to test redirects or use functions.
- Removed Link headers. This was breaking stuff locally and Netlify doesn't have a way to apply headers conditionally without using scripts. Honestly, I'm not sure it's really that important anyway. I checked a bunch of sites including Google, Cloudflare, Netlify, Apple, Stripe, and more. None of them set these headers. This simplifies stuff to remove them.

bridgetown-core/lib/bridgetown-core/configurations/netlify.rb

@@ -1,5 +1,3 @@
 # frozen_string_literal: true
 
 copy_file in_templates_dir("netlify.toml"), "netlify.toml"
-copy_file in_templates_dir("netlify.sh"), "bin/netlify.sh"
-`chmod a+x ./bin/netlify.sh`

bridgetown-core/lib/bridgetown-core/configurations/netlify/netlify.toml

@@ -1,5 +1,17 @@
+[dev]
+  command = "bin/bridgetown dev"
+  targetPort = 4000
+  port = 8888
+  publish = "output"
+  autoLaunch = true
+  framework = "#custom"
+
+[context.dev.build.environment]
+  NODE_ENV = "development"
+  BRIDGETOWN_ENV = "development"
+
 [build]
-  command = "bin/bridgetown deploy && bin/netlify.sh"
+  command = "bin/bridgetown deploy"
   publish = "output"
 
 [build.environment]
@@ -19,14 +31,6 @@
     Referrer-Policy = "no-referrer-when-downgrade"
     Cache-Control = "public, max-age=604800, s-max-age=604800"
 
-[[headers]]
-  for = "/"
-  [headers.values]
-    Link = [
-      "<CSS_PATH>; rel=preload; as=style",
-      "<JS_PATH>; rel=preload; as=script"
-    ]
-
 [[headers]]
   for = "/*.(png|jpg|js|css|svg|woff|ttf|eot|ico|woff2)"
   [headers.values]