Evaluate GA'd version of System.CommandLine

Right now we have a non-GA version of system.commandline. We should move to a released version now that the API is finalized.

At the same time, we can use Spectre.Console as a way to replace the rendering library if needed. The rendering lib has been deprecated. Otherwise, we can see how much we actually use from it and add it into our code. Adding the package is the public guidance, but it's adding external dependency, and we'd need to check if it's ok for a platform package. Aspire already does this for their CLI nonetheless, so there's prior art in this.