(feat): sops from remote endpoint

[lukasmrtvy]

Would be nice to have a feature for referencing remote endpoints.

For example:
sops -d --azure-kv https://sops.vault.azure.net/keys/sops-key/some-string s3::https://s3.amazonaws.com/sops/sops.enc.yaml

go-getter can support:

• http(s)
• git
• gcs
• aws
• PR for Azure Storage (Add Azure Blob Storage Support hashicorp/go-getter#33)

Related: hashicorp/go-getter#222