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/blocs/auth/auth_event.dart

@@ -0,0 +1,55 @@
+import 'package:equatable/equatable.dart';
+
+abstract class AuthEvent extends Equatable {
+  const AuthEvent();
+
+  @override
+  List<Object?> get props => [];
+}
+
+class AuthCheckRequested extends AuthEvent {}
+
+class AuthSignInRequested extends AuthEvent {
+  final String email;
+  final String password;
+
+  const AuthSignInRequested({
+    required this.email,
+    required this.password,
+  });
+
+  @override
+  List<Object?> get props => [email, password];
+}
+
+class AuthSignUpRequested extends AuthEvent {
+  final String email;
+  final String password;
+  final String nom;
+  final String prenom;
+
+  const AuthSignUpRequested({
+    required this.email,
+    required this.password,
+    required this.nom,
+    required this.prenom,
+  });
+
+  @override
+  List<Object?> get props => [email, password, nom, prenom];
+}
+
+class AuthGoogleSignInRequested extends AuthEvent {}
+
+class AuthAppleSignInRequested extends AuthEvent {}
+
+class AuthSignOutRequested extends AuthEvent {}
+
+class AuthPasswordResetRequested extends AuthEvent {
+  final String email;
+
+  const AuthPasswordResetRequested({required this.email});
+
+  @override
+  List<Object?> get props => [email];
+}