Fix copying "dev-404-page.js" to the cache folder on Windows (gatsbyjs#3627)

* Fix images disappearing from rendered markdown files

Fixes gatsbyjs#3608

* Revert invalid indentation changes

* Fix copying "dev-404-page.js" to the cache folder on Windows

Fixes gatsbyjs#2819

* Fix snapshot tests

* Revert invalid improper snapshot test modification

Author: kripod

packages/gatsby/src/bootstrap/__tests__/__snapshots__/load-plugins.js.snap

@@ -2,6 +2,18 @@
 
 exports[`Load plugins Loads plugins defined with an object but without an option key 1`] = `
 Array [
+  Object {
+    "id": "Plugin dev-404-page",
+    "name": "dev-404-page",
+    "nodeAPIs": Array [
+      "createPages",
+    ],
+    "pluginOptions": Object {
+      "plugins": Array [],
+    },
+    "resolve": "",
+    "version": "1.0.0",
+  },
   Object {
     "id": "Plugin component-page-creator",
     "name": "component-page-creator",
@@ -39,18 +51,6 @@ Array [
     "resolve": "",
     "version": "1.0.0",
   },
-  Object {
-    "id": "Plugin dev-404-page",
-    "name": "dev-404-page",
-    "nodeAPIs": Array [
-      "createPages",
-    ],
-    "pluginOptions": Object {
-      "plugins": Array [],
-    },
-    "resolve": "",
-    "version": "1.0.0",
-  },
   Object {
     "id": "Plugin prod-404",
     "name": "prod-404",
@@ -99,6 +99,18 @@ Array [
 
 exports[`Load plugins load plugins for a site 1`] = `
 Array [
+  Object {
+    "id": "Plugin dev-404-page",
+    "name": "dev-404-page",
+    "nodeAPIs": Array [
+      "createPages",
+    ],
+    "pluginOptions": Object {
+      "plugins": Array [],
+    },
+    "resolve": "",
+    "version": "1.0.0",
+  },
   Object {
     "id": "Plugin component-page-creator",
     "name": "component-page-creator",
@@ -136,18 +148,6 @@ Array [
     "resolve": "",
     "version": "1.0.0",
   },
-  Object {
-    "id": "Plugin dev-404-page",
-    "name": "dev-404-page",
-    "nodeAPIs": Array [
-      "createPages",
-    ],
-    "pluginOptions": Object {
-      "plugins": Array [],
-    },
-    "resolve": "",
-    "version": "1.0.0",
-  },
   Object {
     "id": "Plugin prod-404",
     "name": "prod-404",

packages/gatsby/src/bootstrap/load-plugins.js

@@ -133,6 +133,9 @@ module.exports = async (config = {}) => {
   }
 
   // Add internal plugins
+  plugins.push(
+    processPlugin(path.join(__dirname, `../internal-plugins/dev-404-page`))
+  )
   plugins.push(
     processPlugin(
       path.join(__dirname, `../internal-plugins/component-page-creator`)
@@ -148,9 +151,6 @@ module.exports = async (config = {}) => {
       path.join(__dirname, `../internal-plugins/internal-data-bridge`)
     )
   )
-  plugins.push(
-    processPlugin(path.join(__dirname, `../internal-plugins/dev-404-page`))
-  )
   plugins.push(
     processPlugin(path.join(__dirname, `../internal-plugins/prod-404`))
   )

packages/gatsby/src/internal-plugins/dev-404-page/gatsby-node.js

@@ -8,7 +8,7 @@ exports.createPages = async ({ store, boundActionCreators }) => {
     const currentPath = path.join(__dirname, `./raw_dev-404-page.js`)
     const newPath = path.join(program.directory, `.cache`, `dev-404-page.js`)
 
-    fs.copySync(currentPath, newPath)
+    await fs.copy(currentPath, newPath)
 
     createPage({
       component: newPath,