Possibility to use secrets when downloading remote artifacts

[SebastienDegodez]

Reason/Context

See microcks/microcks-testcontainers-node#123

Description

See microcks/microcks-testcontainers-node#123

Implementation ideas

No response

[lbroudoux]

I think documentation in README on how to use this is still missing.

[lbroudoux]

As #74 as been created, we can close this one.