[Feature]: ARM OBO token and header support

### Description of the new feature

We'd like to enable scenarios that'd make it possible to use Az powershell with [ARM OBO token](https://eng.ms/docs/products/arm/rbac/authentication/getting_obo_token).
Assuming the token itself is just a regular AAD access token we'd still need the ability to specify a couple of required headers.

### Proposed implementation details (optional)

A couple of alternatives
- Accept `-Headers` parameters in `Invoke-AzRestMethod`
- Accept the correlationId and OBO token as part of `Connect-AzAccount` and inject it in all subsequent ARM calls