Add Snackbar for opt-in status: Internal User

#### Describe the task
follow up ticket for #886
Internal users editing the opt-in status and final year of report does not get a success snackbar

#### Acceptance Criteria
Given I am an internal user on an operation information page
- [ ] Show success toast "changes saved", each time user changes toggle for opt in status
- [ ] Make final report year expected mandatory and denote with a red asterisk * [wireframe](https://www.figma.com/design/LsDmLDCdnJqI8UahyqvOD8/BCIERS-Designs?node-id=18140-836&t=sXJpGyxPKYhNqt3h-4)
- [ ] show success toast "changes saved" if the default value for "year that final report is expected" got changed by the user

#### Definition of Done

- [ ] first
- [ ] second
- [ ] third

#### Additional context

- Add any other context about the task here.
- Or here

Start at the operation information page and review follow-up ticket #886; the issue names no source files or tests. Compare the requested field marker and notifications with the linked Figma wireframe, then verify both the opt-in toggle and final report year changes show the specified success message.

Written by the indexing model from the issue text.