Azure Scalers: Use our own chained TokenCredential with MSI, WI and CLI

[JorTurFer]

Proposal

We use azure-sdk-for-go in several scaler (and eventually we will migrate others when they are available) and the new identity sdk introduces already defined TokenCredential for several authetication flows. Currently, we have a single option on each case but we could have a chained TokenCredential which tries with all the already configured flows, having a unified code for both pod identities and also for local development.
Now we don't have any way to troubleshoot/debug a scaler that uses azure pod identities as we can't get the token, but if we unify them in a single chained TokenCredential, we could debug it locally, having the same behaviour that we could expect in the cluster, making the experience so much better.

This improvement has some requisites before being doable:

• This upstream issue needs to be solved
• v1.3.0 with official support for WI is required

[JorTurFer]

This can't be done because we have to support split chains because end users could have both auths working together in the same cluster with different roles.