As a customer, speed up my first build/run after doing dotnet new

Initial performance data indicates that the second dotnet run after creating a new application is significantly faster than the first one. Much of that cold-start time is spend spinning up the MSBuild nodes, Roslyn nodes, RAR cache nodes (future), etc.

Since it's highly likely that someone running dotnet new would the turn around and do a dotnet run, we should investigation options for spinning up some of the warm dotnet run processes.

Options.
- Execute a dotnet build in the background
- What happens if the user runs dotnet build before this background build is done warming up?
- Execute a dotnet run in the background
- We don't actually want to run the application though
- Targeted starting of various nodes and processes
- More work but gives us more control over what starts up and when

The cold build had a particularly high CoreCompile call so it may be worth ensuring that any early initialization we do helps with that:
Target: CoreCompile | 3,557.447 |  
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