Refactor signup page to use BLoC pattern and implement authentication repository

- Updated signup.dart to replace Provider with BLoC for state management.
- Created AuthRepository to handle authentication logic and Firestore user management.
- Added TripRepository and UserRepository for trip and user data management.
- Implemented methods for user sign-in, sign-up, and data retrieval in repositories.
- Enhanced trip management with create, update, delete, and participant management functionalities.
- Updated AuthService to include new methods for sign-in and sign-up.
- Removed unnecessary print statements from TripService for cleaner code.
- Added dependencies for flutter_bloc and equatable in pubspec.yaml.

Not tested yet

lib/services/auth_service.dart

@@ -9,7 +9,7 @@ class AuthService {
 
   Stream<User?> get authStateChanges => firebaseAuth.authStateChanges();
 
-  Future<UserCredential> signIn({
+  Future<UserCredential> signInWithEmailAndPassword({
     required String email,
     required String password
   }) async {
@@ -17,7 +17,7 @@ class AuthService {
         email: email, password: password);
   }
 
-  Future<UserCredential> createAccount({
+  Future<UserCredential> signUpWithEmailAndPassword({
       required String email, 
       required String password
     }) async {
@@ -100,5 +100,9 @@ class AuthService {
       rethrow;
     }
   }
+
+  Future signInWithApple() async {
+    // TODO: Implémenter la connexion avec Apple
+  }
   
 }