fix(db-mongodb): query 'in' with a comma-delimited value (#8910)

### What?
Fixes the issue with `in` querying when the collection has a join field.

### Why?
When using `.aggregate`, MongoDB doesn't cast a comma delimited value
for the `$in` operator to an array automatically as it's not handled by
Mongoose.

### How?
Sanitizes the incoming value to an array if it should.

Fixes https://github.com/payloadcms/payload/issues/8901

packages/db-mongodb/src/queries/sanitizeQueryValue.ts

@@ -78,7 +78,11 @@ export const sanitizeQueryValue = ({
           return { operator: formattedOperator, val: undefined }
         }
       }
-    } else if (Array.isArray(val)) {
+    } else if (Array.isArray(val) || (typeof val === 'string' && val.split(',').length > 1)) {
+      if (typeof val === 'string') {
+        formattedValue = createArrayFromCommaDelineated(val)
+      }
+
       formattedValue = formattedValue.reduce((formattedValues, inVal) => {
         const newValues = [inVal]
         if (!hasCustomID) {

test/joins/int.spec.ts

@@ -609,6 +609,24 @@ describe('Joins Field', () => {
       expect(response.data.Category.relatedPosts.docs[0].title).toStrictEqual('test 3')
     })
   })
+
+  it('should work id.in command delimited querying with joins', async () => {
+    const allCategories = await payload.find({ collection: 'categories', pagination: false })
+
+    const allCategoriesByIds = await restClient
+      .GET(`/categories`, {
+        query: {
+          where: {
+            id: {
+              in: allCategories.docs.map((each) => each.id).join(','),
+            },
+          },
+        },
+      })
+      .then((res) => res.json())
+
+    expect(allCategories.totalDocs).toBe(allCategoriesByIds.totalDocs)
+  })
 })
 
 async function createPost(overrides?: Partial<Post>, locale?: Config['locale']) {