Migrate deployment of Tenancy service to Bicep

[JamesDawson]

A spike has been carried-out in this repo and this issue relates to productionising that implementation and replacing the existing deployment scripts.

Including:

1. Support for hosting in Azure Functions & Container Apps
2. Simplified configuration management through use of Azure AppConfiguration
3. Integration with source-controlled deployment configuration work planned here:
   • Add centralised deployment configuration store Marain.Deployment.Template#4