Update Scaleway provider to support config files

[bakhtin]

Description

Update Scaleway provider to support supplying the credentials through config files. A config file can be read from a Secret mounted as a Volume inside the Pod.

Checklist

• Unit tests updated
• End user documentation updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: bakhtin / name: Artyom Bakhtin (783e699)

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[k8s-ci-robot]

Hi @bakhtin. Thanks for your PR.

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[mloiseleur]

/ok-to-test

[mloiseleur]

/lgtm

[bakhtin]

/cc @Raffo @Sh4d1

[Sh4d1]

/lgtm

[Raffo]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Raffo

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