optionally auto detect credentials from env

[universalmind303]

Description

A lot of the credentials variants (especially the object store credentials) usually have env var equivalents that are specified by the provider.

Such as google cloud, it'll look for .config/gcloud/application_default_credentials.json by default. Same goes for AWS, there are many AWS specific env vars that the aws default credentials provider chain will use.

not sure exactly what the UX would be, but I do think it'd be nice if we could auto detect credentials if the user opts in to it.

Possibly through a session var?

set gcp_use_env_credentials = true;
select * from csv_scan('gs://my_bucket/my_file.csv')

CREATE CREDENTIALS azure_creds
    PROVIDER azure
    OPTIONS (
        use_env = true
    );

[tychoish]

I like the second option more than the first, but I haven't thought about it too much, so I could be sold :D