Move the cleanup option to the command line

[m-nash]

Right now there is a cleanup option in the tsp-location.yaml file which is kind of an awkward place to put this and can lead to accidentally checking in with this option turned off.

Instead I think we should move this to a command line option -save-inputs.

This optional flag will be passed into the Typespec-Project-Generate.ps1 script and if it is passed in we will forward this flag to the emitter which can then do nothing or save any files that might be intermediate files similar to codemodel.yaml in autorest. It will also use this flag to decide whether or not to delete the TempTypeSpecFiles folder.

If not all languages support this option in their emitter we can modify the GetEmitterAdditionalOptionsFn to take in this flag and then the language specific implementation can either ignore or return back the emitter option. If we end up making this change I would like to update the signature to take a dictionary to support new params in the future without a breaking signature change.