Snake case for Azure backend configuration

[faustodavid]

Is your feature request related to a problem? Please describe.
Azure backend naming convention is with "-" and the other backends are snake case. This might make it tricky when writing or reading documentation.

For example, the following sample code won't work with azure.
https://github.com/grafana/tempo/blob/main/docs/tempo/website/configuration/parquet.md?plain=1#L47

Describe the solution you'd like
Use snake case in the azure backend configuration file
https://github.com/grafana/tempo/blob/main/tempodb/backend/azure/config.go

Additional context
This will be a breaking change for current Tempo users that uses Azure as the backend. If the team is OK with this, I can create a PR to update the docs and the configuration file.

[joe-elliott]

Yup. I've been meaning to address this for a long time. If you have the time @faustodavid a PR would be much appreciated to correct this. Since we're about to cut 2.0 it would be a good time for a breaking change.

🙏