[Rolodex] Update fidelity of Contact list screens (#2588)

This PR:

- Updates the fidelity of the home screen and contact list screens to near full fidelity
- Renames "Contact Lists" to "Contact Groups". We have multiple collections of contacts, so having lists of lists felt confusing
- Adds more functionality to the data models

Comparison of the two screens against native:

| Native | Flutter |
| --- | --- |
| <img width="418" alt="Screenshot 2025-02-19 at 2 59 58 PM" src="https://github.com/user-attachments/assets/1cc53d19-6bb5-4782-82fa-1a62cd75fd51" /> | <img width="397" alt="Screenshot 2025-02-19 at 2 58 54 PM" src="https://github.com/user-attachments/assets/ddab75f2-4aec-4239-a736-690a3185c196" /> |
| <img width="409" alt="Screenshot 2025-02-19 at 2 59 41 PM" src="https://github.com/user-attachments/assets/ee0d81ee-ae60-47ad-b071-266f39ce9b70" /> | <img width="402" alt="Screenshot 2025-02-19 at 2 58 45 PM" src="https://github.com/user-attachments/assets/88bf22f9-d8bd-40d7-a9ca-f2ded439de6c" /> |

Notably the container widget on the first screen is a placeholder, until a Cupertino collapsable widget is made.

rolodex/lib/data/contact.dart

@@ -3,7 +3,43 @@
 // found in the LICENSE file.
 
 class Contact {
-  Contact({required this.id});
+  Contact({
+    required this.id,
+    required this.firstName,
+    this.middleName,
+    required this.lastName,
+    this.suffix,
+  });
 
   final int id;
+  final String firstName;
+  final String lastName;
+  final String? middleName;
+  final String? suffix;
 }
+
+final johnAppleseed = Contact(id: 0, firstName: 'John', lastName: 'Appleseed');
+final kateBell = Contact(id: 1, firstName: 'Kate', lastName: 'Bell');
+final annaHaro = Contact(id: 2, firstName: 'Anna', lastName: 'Haro');
+final danielHiggins = Contact(
+  id: 3,
+  firstName: 'Daniel',
+  lastName: 'Higgins',
+  suffix: 'Jr.',
+);
+final davidTaylor = Contact(id: 4, firstName: 'David', lastName: 'Taylor');
+final hankZakroff = Contact(
+  id: 5,
+  firstName: 'Hank',
+  middleName: 'M.',
+  lastName: 'Zakroff',
+);
+
+final Set<Contact> allContacts = <Contact>{
+  johnAppleseed,
+  kateBell,
+  annaHaro,
+  danielHiggins,
+  davidTaylor,
+  hankZakroff,
+};