Update dependency management

[sisyphusSmiling]

Description

Now that Flow CLI supports dependency management via flow dependencies ..., it would be most consistent to dogfood the feature in this repository by using it for dependency management.

Relevant PR should update existing dependency management to use CLI's dependency manager. If done in the near future, network dependencies should be pulled from Previewnet, though this will need to be updated once Previewnet is brought down in favor of Testnet and eventually Mainnet once Cadence 1.0 is live on those networks.