Allow gcp-filestore-backups to support multiple filestores

[sgibson91]

https://github.com/2i2c-org/infrastructure/blob/main/helm-charts/images/gcp-filestore-backups/gcp-filestore-backups.py was written to only accept a single name of a filestore instance to create backups for. However, in our terraform code we do actually permit deployment of multiple filestores (if only for the case to functionally permit resizing a GCP Filestore down). Is there a use case for gcp-filestore-backups to also backup multiple filestores in the same project?

What needs to be done?

• Improve gcp-filestore-backups.py to accept multiple filestore names and check each for backups
• Rebuild the gcp-filestore-backups image and update the support chart
• Update support chart to permit an array of filestore names in schema

[yuvipanda]

@sgibson91 yes, you should implement that! Do you need any more information than what you have? If this feels refined enough, please put this card in refined as part of the epic you're working on, and pick it up when you're done with the existing tasks there!

Thanks for catching this.