248 Updated accept donor request and notification model and service

Fixes #248

What kind of change does this PR introduce (check at least one)

Provide a brief overview of the changes introduced in this pull request.

Link to the relevant issue(s) or provide a clear description of the problem or feature being addressed.

[x] I have tested these changes locally and they function as expected.
[ ] I have added or updated necessary documentation to reflect the changes.
[ ] I have followed the project's coding style and guidelines.
[ ] I have added appropriate test coverage to ensure the changes are functioning correctly.
[ ] I have checked for any potential conflicts with other branches or pull requests.
[ ] I have updated necessary OpenAPI specs

If you have any specific requests or suggestions for reviewers, mention them here.

If applicable, provide any additional screenshots or GIFs that showcase the changes made in this pull request.

If applicable, provide a link to a live demo or deployment where the changes can be reviewed.

If there are any known issues or limitations with the changes made in this pull request, describe them here.

Add any additional notes or comments you think are relevant to this pull request.

Please assess risk & follow up on deployment of this PR. Elaborate your choice if selecting anything other than 'No risk'.