Added component change notification

core/openapi.yaml

notification/openapi.yaml

notification/pom.xml

...cation/src/main/java/cz/muni/pa165/config/MailConfig.java

...rc/main/java/cz/muni/pa165/facade/NotificationFacade.java

.../main/java/cz/muni/pa165/rest/NotificationController.java

...n/java/cz/muni/pa165/rest/exceptionhandling/ApiError.java

.../exceptionhandling/CustomRestGlobalExceptionHandling.java

.../main/java/cz/muni/pa165/service/NotificationService.java

notification/src/main/resources/application.properties

...on/src/test/java/cz/muni/pa165/rest/IntegrationTests.java

...t/java/cz/muni/pa165/rest/NotificationControllerTest.java