Fix bugs and add tests for timelines in collections (#20798)

frontend/src/metabase-types/api/mocks/timeline.ts

...lections/components/CollectionHeader/CollectionHeader.jsx

frontend/src/metabase/components/Modal.jsx

...rc/metabase/core/components/DateSelector/DateSelector.tsx

frontend/src/metabase/core/components/Input/Input.styled.tsx

...d/src/metabase/entities/containers/EntityObjectLoader.jsx

...imelines/components/DeleteEventModal/DeleteEventModal.tsx

...omponents/DeleteEventModal/DeleteEventModal.unit.spec.tsx

...se/timelines/components/EditEventModal/EditEventModal.tsx

...es/components/EditEventModal/EditEventModal.unit.spec.tsx

...elines/components/EditTimelineModal/EditTimelineModal.tsx

...ponents/EditTimelineModal/EditTimelineModal.unit.spec.tsx

...abase/timelines/components/EventCard/EventCard.styled.tsx

...se/timelines/components/EventCard/EventCard.unit.spec.tsx

.../components/EventEmptyState/EventEmptyState.unit.spec.tsx

...se/timelines/components/EventList/EventList.unit.spec.tsx

.../LoadingAndErrorWrapper/LoadingAndErrorWrapper.styled.tsx

...ponents/LoadingAndErrorWrapper/LoadingAndErrorWrapper.tsx

...base/timelines/components/LoadingAndErrorWrapper/index.ts

...e/timelines/components/ModalHeader/ModalHeader.styled.tsx