.NET Standard 2.0 worker requirements

Related to [recent work](https://github.com/Azure/azure-functions-dotnet-worker/pull/799) on the worker repo, this epic is to track a collection of investments necessary to support that worker from the rest of the product.

(child items listed below to be replaced with public work item links as those are generated, where appropriate)

- Validation with metadata generator
- List a preview version of the package with the additional TFM
- Make sure logs appropriately identify the version (not just ".NET Isolated" like you could have for .NET 6, too)
- https://github.com/Azure/azure-functions-templates/issues/1186
- https://github.com/Azure/azure-functions-tooling-feed/issues/330
- ~~`az functionapp create` should reject requests for this runtime targeting Linux~~ - Update: the stacks API should cover us for creation gestures now. We should double-check this during the validation pass for that work.
- https://github.com/Azure/azure-functions-core-tools/issues/2995
- https://github.com/Azure/azure-functions-dotnet-worker/issues/857
- https://github.com/Azure/azure-functions-dotnet-worker/issues/858
- Ensure that the host service for remote debugging returns the .NET version of the running process.
- (Client tool updates - to be expanded based on in-flight discussions)
- (Client tool validations - to be expanded based on in-flight discussions)
- Docs work (tracked in internal repo)