feat: add find to payloadDataLoader to cache local API queries (#11685)

### What?
Extends our dataloader to add a momiozed payload find function. This way
it will cache the query for the same find request using a cacheKey from
find operation args.

### Why?
This was needed internally for `filterOptions` that exist in an array or
other sitautions where you have the same exact query being made and
awaited many times.

### How?

- Added `find` to payloadDataLoader. Marked `@experimental` in case it
needs to change.
- Created a cache key from the args
- Validate filterOptions changed from `payload.find` to
`payloadDataLoader.find`
- Made `payloadDataLoader` no longer optional on `PayloadRequest`, since
other args are required which are created from createLocalReq (context
for example), I don't see a reason why dataLoader shouldn't be required
also.

Example usage: 
```ts
const result = await req.payloadDataLoader.find({
    collection,
    req,
    where,
  })
```

test/database/postgres-vector.int.spec.ts

@@ -1,5 +1,6 @@
 /* eslint-disable jest/require-top-level-describe */
-import { PostgresAdapter } from '@payloadcms/db-postgres/types'
+import type { PostgresAdapter } from '@payloadcms/db-postgres/types'
+
 import { cosineDistance, desc, gt, sql } from 'drizzle-orm'
 import path from 'path'
 import { buildConfig, getPayload } from 'payload'

test/dataloader/int.spec.ts

@@ -1,6 +1,7 @@
-import type { Payload } from 'payload'
+import type { CollectionSlug, Payload } from 'payload'
 
 import path from 'path'
+import { createLocalReq } from 'payload'
 import { fileURLToPath } from 'url'
 
 import type { NextRESTClient } from '../helpers/NextRESTClient.js'
@@ -28,7 +29,9 @@ describe('dataloader', () => {
       },
     })
 
-    if (loginResult.token) token = loginResult.token
+    if (loginResult.token) {
+      token = loginResult.token
+    }
   })
 
   afterAll(async () => {
@@ -187,4 +190,26 @@ describe('dataloader', () => {
       expect(innerMostRelationship).toStrictEqual(relationB.id)
     })
   })
+
+  describe('find', () => {
+    it('should call the same query only once in a request', async () => {
+      const req = await createLocalReq({}, payload)
+      const spy = jest.spyOn(payload, 'find')
+
+      const findArgs = {
+        collection: 'items' as CollectionSlug,
+        req,
+        depth: 0,
+        where: {
+          name: { exists: true },
+        },
+      }
+
+      void req.payloadDataLoader.find(findArgs)
+      void req.payloadDataLoader.find(findArgs)
+      await req.payloadDataLoader.find(findArgs)
+
+      expect(spy).toHaveBeenCalledTimes(1)
+    })
+  })
 })