Description.
Added permissions for report preventPurge function.

To reproduce

1. Login as admin;
2. Create Virtual Data Source as ds_1 and Virtual Data Point as dp_1 (no change, binary);
3. Create User Profile as pro_1 with read permission for ds_1 - dp_1;
4. Create non-admin user as usr_1, with profile pro_1;
5. Login as usr_1;
6. Go to 'Modern interface' -> 'Reports';
7. On 'Templates' click on 'New report', name set rep_1 with points: ds_1 - dp_1;
8. Click on 'Run now' on rep_1;
9. Go to 'Instances';
10. In column 'Do not purge' click checbox -> error
11. Refesh page and go to 'Instances' -> no checked -> error