Add trigger for periodic topology snapshots

[julientinguely-da]

fixes #1133

test bucket: https://console.cloud.google.com/storage/browser/da-splice-topology-snapshots;tab=objects?forceOnBucketsSortingFiltering=true&project=da-cn-splice&prefix=&forceOnObjectsSortingFiltering=false

The plan would be to activate it on sv1 in our production clusters (will be available from 0.5.2).

Remaining:

• refactor code
• add test
• pulumi changes

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