Mirror KC behavior for delete-submission permission

[jnm]

In KoBoCAT, if you have permission to edit submissions, you can delete them as well. By contrast, KPI only assigns delete_submissions to the owner, as a calculated permission that is not stored in the database. After completing #2281, we should:

1. Change the calculation logic to include delete_submissions in the list of permissions for anyone who has change_submissions;
2. Change the KPI submissions API to check for delete_submissions instead of change_submissions. See here the test that needs to be updated:

   kpi/kpi/tests/test_api_submissions.py

   Lines 184 to 192 in 4616238

   	def test_delete_submission_shared_other_write(self):
   	self._other_user_login(True)
   	self.asset.assign_perm(self.anotheruser, "change_submissions")
   	submission = self.submissions[0]
   	url = self.asset.deployment.get_submission_detail_url(submission.get("id"))
   	response = self.client.delete(url,
   	content_type="application/json",
   	HTTP_ACCEPT="application/json")
   	self.assertEqual(response.status_code, status.HTTP_204_NO_CONTENT)