Feature request: Allow passing a valid context to encrypt/decrypt operations with AWS, Azure, GCP, PGP and HashiCorp Vault

[matheuscscp]

Hi 👋

Right now we pass context.Background()/context.TODO() to the encrypt/decrypt operations internally. It would be valuable to accept a context in these operations and pass it down instead. As SDK users we'd like to do that in CNCF Flux. The SOPS CLI could also benefit from this passing a context tied to the SIGTERM and SIGINT signals.