load_stac: how to deal with authentication

[jdries]

various stac endpoints require a form of authentication AWS: S3 credentials Terrascope: OIDC ( MS planetary computer: some sort of custom mechanism

but our load_stac currently does not support any of these in the past, we have added possibilities to handle this backend side, which remains a valid option, but supporting it client side makes a lot of sense as well.

To be investigated what we can do for all these mechanisms.

[jdries]

The mechanism for mspc is probably easiest, because it in fact does not really require credentials. We could thus detect the use of an mspc collection, and simply sign the href's before using them.

[bossie]

Related: #760

[VictorVerhaert]

there is a stac extension that covers authentication: https://github.com/stac-extensions/authentication