[ETL-628] Rework S3 event config lambda (#108)

* Delete preexisting S3 event notification before creation

* Rework s3_event_config lambda to index configs from s3 prefix/suffix

* Changes related to Prefix/prefix FilterRule discrepancy

There is a bug in moto/AWS where moto only allows filter rules with lowercase
`Name` values in put_bucket_notification_configuration calls. So to normalize
our notification configurations when comparing configurations obtained via a
GET with configurations to be utilized in a PUT (as we do in the function
`notification_configuration_matches`), we make the `Name` values lower case in
when comparing notification configurations.

When calling get_bucket_notification_configuration, the `Name` value is
always capitalized, whereas moto requires us to use lowercase `Name`
values when calling put_bucket_notification_configuration.

* Remove event notification for namespace upon branch deletion

.github/workflows/cleanup.yaml

@@ -20,6 +20,17 @@ jobs:
           role_session_name: GitHubActions-${{ github.repository_owner }}-${{ github.event.repository.name }}-${{ github.run_id }}
           python_version: 3.9
 
+      - name: Delete S3 event notification for this namespace
+        uses: gagoar/invoke-aws-lambda@v3
+        with:
+          AWS_ACCESS_KEY_ID: ${{ env.AWS_ACCESS_KEY_ID }}
+          AWS_SECRET_ACCESS_KEY: ${{ env.AWS_SECRET_ACCESS_KEY }}
+          AWS_SESSION_TOKEN: ${{ env.AWS_SESSION_TOKEN }}
+          REGION: ${{ env.AWS_REGION }}
+          FunctionName: ${{ github.event.ref }}-S3EventConfig
+          Payload: '{"RequestType": "Delete"}'
+          LogType: Tail
+
       - name: Remove sceptre stacks
         run: pipenv run sceptre --debug --var namespace=${{ github.event.ref }} delete develop/namespaced --yes