* Remove gRPC and convert PricingClient to HttpClient wrapper
* Add PlanType.GetProductTier extension
Many instances of StaticStore use are just to get the ProductTierType of a PlanType, but this can be derived from the PlanType itself without having to fetch the entire plan.
* Remove invocations of the StaticStore in non-Test code
* Deprecate StaticStore entry points
* Run dotnet format
* Matt's feedback
* Run dotnet format
* Rui's feedback
* Run dotnet format
* Replacements since approval
* Run dotnet format
* chore: set up a `CODEOWNERS` space for platform
* chore: move sql objects for `Installation` to platform's domain
* chore: move `Installation` and `PushRelay` code to platform's domain
