Use Arcade to install tools in CI builds

[dougbu]

Once dotnet/arcade#4072 (an epic) is complete, we'll be able to reduce use of OS-specific installation scripts and rely on Arcade to install necessary tooling. See https://github.com/dotnet/arcade/blob/master/Documentation/Policy/ToolsetPolicy.md for some reasons why using Arcade would be helpful.

May also need some https://netcorenativeassets.blob.core.windows.net/ assets to be renamed e.g. downloads for java, git and tar might not follow the conventions (haven't checked lately).

[dougbu]

@markwilkie about when should we expect the dotnet/arcade#4072 work to complete?

[markwilkie]

Unfortunately this epic is not scheduled yet. :( If it ends up being less work for y'all to modify the feature in arcade, I'd be open to that idea - even if it wasn't fully implemented.