Add logout functionality in controller and datastore access

<UserStory> AUTH003: Logout User </UserStory>

<Changes>
- Added logout() method in ZenvyController and AuthenticationManagementService
- Implemented logout handling in AuthenticationManagementService
</Changes>

<Review>
Smitha Mohan
</Review>

Trenser.Zenvy/Trenser.Zenvy/controllers/ZenvyController.cpp

@@ -8,6 +8,7 @@ AuthenticationContext ZenvyController::login(const std::string& email, const std
 
 void ZenvyController::logout()
 {
+	m_authenticationManagementService->logout();
 }
 
 void ZenvyController::changePassword(const std::string& password) const

Trenser.Zenvy/Trenser.Zenvy/datastores/DataStore.cpp

@@ -24,4 +24,10 @@ void DataStore::setAuthenticatedEmployee(std::shared_ptr<Employee> authenticated
 employeeMap& DataStore::getEmployees()
 {
 	return m_employees;
-}
+}
+
+std::shared_ptr<Employee>& DataStore::getAuthenticatedUser()
+{
+	return m_authenticatedEmployee;
+}
+

Trenser.Zenvy/Trenser.Zenvy/datastores/DataStore.h

@@ -36,6 +36,7 @@ public:
     DataStore(DataStore&&) = delete;
     DataStore& operator=(DataStore&&) = delete;
 	employeeMap& getEmployees();
+    std::shared_ptr<Employee>& getAuthenticatedUser();
     logMap& getLogs();
     std::shared_ptr<Employee>& getAuthenticatedEmployee();
     void setAuthenticatedEmployee(std::shared_ptr < Employee>);

Trenser.Zenvy/Trenser.Zenvy/services/AuthenticationManagementService.cpp

@@ -59,3 +59,12 @@ void AuthenticationManagementService::changePassword(const std::string& password
 		throw std::runtime_error("User not found");
 	}
 }
+
+void AuthenticationManagementService::logout() {
+	if (m_dataStore.getAuthenticatedUser()) {
+		m_dataStore.getAuthenticatedUser() = nullptr;
+	}
+	else {
+		throw std::runtime_error("No user currently logged In...");
+	}
+}