Support for Service Principal with certificate (no password)

[zioproto]

Purpose

To support the CodeSpaces scenario: In case you can't create a Service Principal with password (for example because of tenant policy) you need to create a Service Principal with certificate.

Does this introduce a breaking change?

[ ] Yes
[ X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[X ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

Create a service principal with certificate:

az ad sp create-for-rbac --role="Owner" --scopes="/subscriptions/<SUBSCRIPTION_ID>" --create-cert -o json

Populate the CodeSpace secrets:

ARM_CLIENT_ID
ARM_CLIENT_SECRET
ARM_TENANT_ID

The certificate secret must be populated like this:

ARM_CLIENT_CERTIFICATE=$(cat cert-and-private-key.pem| base64)

Follow the tutorial steps in the Readme.