NF template config location update

[anngvu]

In Slack @afwillia announced that we can maintain the templates config.json somewhere and DCA will reference the link.

the template dropdown config and logo will be referenced by a URL, not the filepath in data_curator_config. This means those files can live elsewhere, like your data model repo.

This is recommended to reduce external PRs just to change the template menu/get faster direct updates.

@allaway @cconrad8 for awareness -- this is for staging first, we'll make this change for prod as well after this is merged.