Feature - add HashiCorp Vault secret provider

[stijnmoreels]

Added a new project (NuGet package) with a secret provider that will interact wtih the KeyValue secret of a HashiCorp Vault.
This feature contains:

• The ISecretProvider implementation itself
• User-friendly extensions to register in the secret store for:
  • UserPass authentication
  • Kubernetes authentication
  • Custom configuration
• Unit tests for all components
• Integration test that interact with a fresh HashiCorp Vault instance running in 'dev server' mode for:
  • UserPass authentication
• Feature docs update with examples of how this secret provider can be added to the secret store, with examples of what is required and by default provided and can be overridden.

Relates to #159

[arcus-automation]

A new preview package for Arcus.Security.All is available on MyGet.

You can pull it locally via the CLI:

PM> Install-Package Arcus.Security.All -Version 20200821.0.0-PR-165 -Source https://www.myget.org/F/arcus/api/v3/index.json

[arcus-automation]

A new preview package for Arcus.Security.All is available on MyGet.

You can pull it locally via the CLI:

PM> Install-Package Arcus.Security.All -Version 20200825.0.0-PR-165 -Source https://www.myget.org/F/arcus/api/v3/index.json

[arcus-automation]

A new preview package for Arcus.Security.All is available on MyGet.

You can pull it locally via the CLI:

PM> Install-Package Arcus.Security.All -Version 20200826.0.0-PR-165 -Source https://www.myget.org/F/arcus/api/v3/index.json

[tomkerkhove]

Not yet created integration test for Kuberetes authentication bc that would require me to create a Kubernetes service account (extra costs per month) and maybe not the worth the cost for that?
Of course if there's a way that this can be up shortcutted, and there's a way to test this external call by setting up a test server that validates the JWT token for us... we could maybe go that route.

Let's add a dedicated issue where we deploy a container to a Kind cluster and run against that.

[tomkerkhove]

LGTM, the only suggestion I would have is to move out the Kubernetes auth unless you are certain that it already works fine?

[stijnmoreels]

LGTM, the only suggestion I would have is to move out the Kubernetes auth unless you are certain that it already works fine?

I can honestly say I don't know anything for certain 😅.
We're just using the already available Kubernetes authentication type and pass along the values, so only if VaultSharp has some problems, I don't think that there's something wrong with it. But again, I'm nothing certain.

[tomkerkhove]

Good enough!

[arcus-automation]

A new preview package for Arcus.Security.All is available on MyGet.

You can pull it locally via the CLI:

PM> Install-Package Arcus.Security.All -Version 20200831.0.0-PR-165 -Source https://www.myget.org/F/arcus/api/v3/index.json