Merge branch 'editor-intro-pages' into 'dp-platkova'

frontend/src/editor/EditorPage/index.tsx

frontend/src/editor/ExerciseInformationForm/index.tsx

frontend/src/editor/IntroductionForm/index.tsx

frontend/src/editor/Navbar/index.tsx

frontend/src/editor/useEditorStorage.tsx

frontend/src/editor/utils.tsx

...itor/create/activity-specification/[activityId]/index.tsx

.../src/pages/editor/create/activity-specification/index.tsx

frontend/src/pages/editor/create/exercise-information.tsx

frontend/src/pages/editor/create/injects.tsx

frontend/src/pages/editor/create/introduction.tsx

frontend/src/pages/editor/create/learning-objectives.tsx

frontend/src/pages/editor/create/participants.tsx

frontend/src/router.ts