fix: #1870 and #1859

* chore: ensures relationship fields react to locale changes in the admin panel - fixes #1870

* chore: patches in default values for fields, and localized fields using fallbacks - fixes #1859

* chore: organizes field localization and sanitizing

* Revert "Feat/1180 loading UI enhancements"

* Feat/1180 loading UI enhancements

* chore: safely sets tab if name field, only sets fallback value if it exists

* chore: adds test to ensure text fields use fallback locale value when empty

test/localization/int.spec.ts

@@ -98,6 +98,28 @@ describe('Localization', () => {
       expect(localized.title.es).toEqual(spanishTitle);
     });
 
+    it('should fallback to english translation when empty', async () => {
+      const updated = await payload.update<LocalizedPost>({
+        collection,
+        id: post1.id,
+        locale: spanishLocale,
+        data: {
+          title: '',
+        },
+      });
+
+      expect(updated.title).toEqual(englishTitle);
+
+      const localizedFallback = await payload.findByID<LocalizedPostAllLocale>({
+        collection,
+        id: post1.id,
+        locale: 'all',
+      });
+
+      expect(localizedFallback.title.en).toEqual(englishTitle);
+      expect(localizedFallback.title.es).toEqual('');
+    });
+
     describe('querying', () => {
       let localizedPost: LocalizedPost;
       beforeEach(async () => {