In order to make this work reasonably we can't avoid using some funny
heuristics, which are somewhat reasonable to apply within the context of
Terraform itself but would not be good to add to the general "logutils".
Specifically, this is adding the additional heuristic that lines starting
with spaces are continuation lines and so should inherit the log level
of the most recent non-continuation line.
* vendor updates
- updating to v21.3.0 of github.com/Azure/azure-sdk-for-go
- updating to v10.15.4 of github.com/Azure/go-autorest
- vendoring github.com/hashicorp/go-azure-helpers @ 0.1.1
* backend/azurerm: refactoring to use the new auth package
- refactoring the backend to use a shared client via the new auth package
- adding tests covering both Service Principal and Access Key auth
- support for authenticating using a proxy
- rewriting the backend documentation to include examples of both authentication types
* switching to use the build-in logging function
* documenting it's also possible to retrieve the access key from an env var
James Bardin