feat: add join field config where property (#8973)

### What?

Makes it possible to filter join documents using a `where` added
directly in the config.


### Why?

It makes the join field more powerful for adding contextual meaning to
the documents being returned. For example, maybe you have a
`requiresAction` field that you set and you can have a join that
automatically filters the documents to those that need attention.

### How?

In the database adapter, we merge the requested `where` to the `where`
defined on the field.
On the frontend the results are filtered using the `filterOptions`
property in the component.

Fixes
https://github.com/payloadcms/payload/discussions/8936
https://github.com/payloadcms/payload/discussions/8937

---------

Co-authored-by: Sasha <64744993+r1tsuu@users.noreply.github.com>

test/joins/config.ts

@@ -9,7 +9,13 @@ import { Singular } from './collections/Singular.js'
 import { Uploads } from './collections/Uploads.js'
 import { Versions } from './collections/Versions.js'
 import { seed } from './seed.js'
-import { localizedCategoriesSlug, localizedPostsSlug } from './shared.js'
+import {
+  localizedCategoriesSlug,
+  localizedPostsSlug,
+  postsSlug,
+  restrictedCategoriesSlug,
+  restrictedPostsSlug,
+} from './shared.js'
 
 const filename = fileURLToPath(import.meta.url)
 const dirname = path.dirname(filename)
@@ -60,6 +66,53 @@ export default buildConfigWithDefaults({
         },
       ],
     },
+    {
+      slug: restrictedCategoriesSlug,
+      admin: {
+        useAsTitle: 'name',
+      },
+      fields: [
+        {
+          name: 'name',
+          type: 'text',
+        },
+        {
+          // this field is misconfigured to have `where` constraint using a restricted field
+          name: 'restrictedPosts',
+          type: 'join',
+          collection: postsSlug,
+          on: 'category',
+          where: {
+            restrictedField: { equals: 'restricted' },
+          },
+        },
+      ],
+    },
+    {
+      slug: restrictedPostsSlug,
+      admin: {
+        useAsTitle: 'title',
+      },
+      fields: [
+        {
+          name: 'title',
+          type: 'text',
+        },
+        {
+          name: 'restrictedField',
+          type: 'text',
+          access: {
+            read: () => false,
+            update: () => false,
+          },
+        },
+        {
+          name: 'category',
+          type: 'relationship',
+          relationTo: restrictedCategoriesSlug,
+        },
+      ],
+    },
   ],
   localization: {
     locales: ['en', 'es'],