dotnet up shadowing dotnet commands is slow?

[nagilson]

Add a dotnetup dotnet command to forward to the user-local install root. That way if the PATH isn't correct but dotnetup is on the path you still have a way to access the user-local dotnet. (For this to be more useful, we need to have a way of installing dotnetup itself and adding dotnetup to the path).

[nagilson]

We can also alias this as 'dotnetup do' which is more concise, leans into the 'dotnet' call by starting with 'do' but still uses a verb command that's an actual word and describes what we want, which is to 'run' dotnet and 'do' the command ('pack', etc)

[nagilson]

this is done but we heard from @marcpopMSFT that it might be slow on windows so we should investigate.

[nagilson]

the tests for the dotnetup dotnet command are also not as thorough as Id like and somewhat wasteful. this should be improved.

#53865 (comment)

I agree and don't love these tests - what this does do is ensure that the dotnetup dotnet.exe is used in place of the dotnet.exe on the PATH, and that it parses args transparently. This replaces the 'dotnet' command invocation itself to make it do nothing but everything else remains the same. I'd also like to fix the part where it duplicates the process input args and makes sure the command does it, but as it will be tough to review here, I'll track that here