fix(plugin-import-export): csv export column order (#12258)

### What?
The order of fields, when specified for the create export function was
not used for constructing the data. Now the fields order will be used.

### Why?
This is important to building CSV data for consumption in other systems.

### How?
Adds logic to handle ordering the field values assigned to the export
data prior to building the CSV.

test/plugin-import-export/int.spec.ts

@@ -1,5 +1,6 @@
 import type { CollectionSlug, Payload } from 'payload'
 
+import fs from 'fs'
 import path from 'path'
 import { fileURLToPath } from 'url'
 
@@ -221,6 +222,39 @@ describe('@payloadcms/plugin-import-export', () => {
       expect(data[0].array_1_field2).toStrictEqual('baz')
     })
 
+    it('should create a CSV file with columns matching the order of the fields array', async () => {
+      const fields = ['id', 'group.value', 'group.array.field1', 'title', 'createdAt', 'updatedAt']
+      const doc = await payload.create({
+        collection: 'exports',
+        user,
+        data: {
+          collectionSlug: 'pages',
+          fields,
+          format: 'csv',
+          where: {
+            title: { contains: 'Title ' },
+          },
+        },
+      })
+
+      const exportDoc = await payload.findByID({
+        collection: 'exports',
+        id: doc.id,
+      })
+
+      expect(exportDoc.filename).toBeDefined()
+      const expectedPath = path.join(dirname, './uploads', exportDoc.filename as string)
+      const buffer = fs.readFileSync(expectedPath)
+      const str = buffer.toString()
+
+      // Assert that the header row matches the fields array
+      expect(str.indexOf('id')).toBeLessThan(str.indexOf('title'))
+      expect(str.indexOf('group_value')).toBeLessThan(str.indexOf('title'))
+      expect(str.indexOf('group_value')).toBeLessThan(str.indexOf('group_array'))
+      expect(str.indexOf('title')).toBeLessThan(str.indexOf('createdAt'))
+      expect(str.indexOf('createdAt')).toBeLessThan(str.indexOf('updatedAt'))
+    })
+
     it('should create a file for collection csv from array.subfield', async () => {
       let doc = await payload.create({
         collection: 'exports',