.NET Core BA
User stories
As a Setup developer I can write my Bootstrapper Application in .NET Core and then publish it SCD-style (Self Contained Deployment) such that I can write my BA in managed code without relying on anything being installed on the runtime machine.
As a Setup developer I can write my Bootstrapper Application in .NET Core and then publish it FDD-style (Framework Dependent Deployment) such that I can write my BA in managed code on .NET Core and not bloat the bundle with the runtime.
Proposal
Create a new BA in BalExtension named DotNetCoreBootstrapperApplicationHost.
Create new element bal:WixDotNetCoreBootstrapperApplicationHost based on WixManagedBootstrapperApplicationHost.
Add attribute bal:SelfContainedDeployment of YesNoType to the WixDotNetCoreBootstrapperApplicationHost element so the BA knows how to load the .NET Core Runtime. This is required because there is not a single API that can load the runtime from an SCD-style and an FDD-style deployment. If no and the runtime fails to load, it will show the mbapreq. If yes and the runtime fails to load (because it has native dependencies and relies on running on relatively up to date OS's), it will show an error message similarly to ManagedBootstrapperApplicationHost running on .NET 4.5.2 on Win7 RTM.
Add attribute bal:BAFactoryAssembly of YesNoType to the Payload element so the BA knows which assembly has the BootstrapperApplicationFactoryAttribute.
Considerations
1) .NET Core provides multiple ways to host the runtime. The method for FDD-style deployments is nethost which is a Nuget package and will likely need to be updated regularly. Unfortunately, all hosting methods require copying a header file from the .NET Core repo into our repo.