fix(gatsby-source-contentful): De-dupe type names (#30834)

* fix(gatsby-source-contentful): De-dupe layout type name

* Add placeholder type too

(cherry picked from commit 71ec0cd)

packages/gatsby-source-contentful/src/extend-node-type.js

@@ -23,6 +23,8 @@ const {
   ImageFormatType,
   ImageResizingBehavior,
   ImageCropFocusType,
+  ImageLayoutType,
+  ImagePlaceholderType,
 } = require(`./schemes`)
 
 // By default store the images in `.cache` but allow the user to override
@@ -790,6 +792,25 @@ exports.extendNodeType = ({ type, store }) => {
         type: GraphQLInt,
         defaultValue: 50,
       },
+      layout: {
+        type: ImageLayoutType,
+        description: stripIndent`
+            The layout for the image.
+            CONSTRAINED: Resizes to fit its container, up to a maximum width, at which point it will remain fixed in size. 
+            FIXED: A static image size, that does not resize according to the screen width
+            FULL_WIDTH: The image resizes to fit its container, even if that is larger than the source image.
+            Pass a value to "sizes" if the container is not the full width of the screen.
+        `,
+      },
+      placeholder: {
+        type: ImagePlaceholderType,
+        description: stripIndent`
+            Format of generated placeholder image, displayed while the main image loads.
+            BLURRED: a blurred, low resolution image, encoded as a base64 data URI (default)
+            DOMINANT_COLOR: a solid color, calculated from the dominant color of the image.
+            TRACED_SVG: a low-resolution traced SVG of the image.
+            NONE: no placeholder. Set the argument "backgroundColor" to use a fixed background color.`,
+      },
       formats: {
         type: GraphQLList(ImageFormatType),
         description: stripIndent`

packages/gatsby-source-contentful/src/schemes.js

@@ -11,6 +11,25 @@ const ImageFormatType = new GraphQLEnumType({
   },
 })
 
+const ImageLayoutType = new GraphQLEnumType({
+  name: `ContentfulImageLayout`,
+  values: {
+    FIXED: { value: `fixed` },
+    FULL_WIDTH: { value: `fullWidth` },
+    CONSTRAINED: { value: `constrained` },
+  },
+})
+
+const ImagePlaceholderType = new GraphQLEnumType({
+  name: `ContentfulImagePlaceholder`,
+  values: {
+    DOMINANT_COLOR: { value: `dominantColor` },
+    TRACED_SVG: { value: `tracedSVG` },
+    BLURRED: { value: `blurred` },
+    NONE: { value: `none` },
+  },
+})
+
 const ImageResizingBehavior = new GraphQLEnumType({
   name: `ImageResizingBehavior`,
   values: {
@@ -59,6 +78,8 @@ const ImageCropFocusType = new GraphQLEnumType({
 })
 
 module.exports = {
+  ImageLayoutType,
+  ImagePlaceholderType,
   ImageFormatType,
   ImageResizingBehavior,
   ImageCropFocusType,