Dependency drift across .NET 8 and .NET 9 packages

### Product

dotnet CLI (dotnet new)

### Describe The Bug

Chatted with @sayedihashimi and @phenning today about if/when VS should update to 9.x Template Engine packages, and we saw some discrepancies that are concerning.

.NET 8 package:

.NET 9 package:

The big problems I see are:
* the .net framework TFM has floated to something VS can't use - net481. VS requires net472 currently. This comes from the Arcade NetFrameworkCurrent property I think?
* the NS2.0 dependencies dropped the System. deps, which may require work from Phil to consume (he mentioned missing deps in the past)

Were these on purpose? Do we need to have tests to pin the expectations of the VS host so we don't unwittingly violate them?

### To Reproduce

N/A

### dotnet Info

N/A

### Visual Studio Version

_No response_

### Additional context

_No response_