fix(ui): significantly optimizes relationship field (#8063)

## Description

Reduces the number of client-side requests made by the relationship
field component, and fixes the visual "blink" of the field's value on
initial load. Does so through a new `useIgnoredEffect` hook that allows
this component's effects to be precisely triggered based on whether a
only _subset_ of its dependencies have changed, which looks something
like this:

```tsx
// ...
useIgnoredEffect(() => {
  // Do something
}, [deps], [ignoredDeps])
```

"Ignored deps" are still treated as normal dependencies of the
underlying `useEffect` hook, but they do not cause the provided function
to execute. This is useful if you have a list of dependencies that
change often, but need to scope your effect's logic to explicit
dependencies within that list. This is a typical pattern in React using
refs, just standardized within a reusable hook.

This significantly reduces the overall number of re-renders and
duplicative API requests within the relationship field because the
`useEffect` hooks that control the fetching of these related documents
were running unnecessarily often. In the future, we really ought to
leverage the `RelationshipProvider` used in the List View so that we can
also reduce the number of duplicative requests across _unrelated fields_
within the same document.

Before:


https://github.com/user-attachments/assets/ece7c85e-20fb-49f6-b393-c5e9d5176192

After:


https://github.com/user-attachments/assets/9f0a871e-f10f-4fd6-a58b-8146ece288c4

- [x] I have read and understand the
[CONTRIBUTING.md](https://github.com/payloadcms/payload/blob/main/CONTRIBUTING.md)
document in this repository.

## Type of change

- [x] Bug fix (non-breaking change which fixes an issue)

## Checklist:

- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] Existing test suite passes locally with my changes

test/databaseAdapter.ts

@@ -1,13 +1,16 @@
-// DO NOT MODIFY. This file is automatically generated in initDevAndTest.ts
 
-import { mongooseAdapter } from '@payloadcms/db-mongodb'
+  // DO NOT MODIFY. This file is automatically generated in initDevAndTest.ts
 
-export const databaseAdapter = mongooseAdapter({
-  url:
-    process.env.MONGODB_MEMORY_SERVER_URI ||
-    process.env.DATABASE_URI ||
-    'mongodb://127.0.0.1/payloadtests',
-  collation: {
-    strength: 1,
-  },
-})
+  
+  import { mongooseAdapter } from '@payloadcms/db-mongodb'
+
+  export const databaseAdapter = mongooseAdapter({
+    url:
+      process.env.MONGODB_MEMORY_SERVER_URI ||
+      process.env.DATABASE_URI ||
+      'mongodb://127.0.0.1/payloadtests',
+    collation: {
+      strength: 1,
+    },
+  })
+