cli: anchor expand

[paul-schaaf]

1. ship cargo expand with anchor and make it available through anchor expand
2. anchor expand also redirects the output into a file in a directory that we include in .gitignore
3. instead of overwriting existing files in that directory, it creates a new one every time with some informative name. maybe the time , anchor-version etc.

to me this isn't that important and just a nice little ux improvement but maybe there are more reasons this would be a good idea (or wouldn't be)

[tomlinton]

This is a good idea - even if it is just to encourage people to expand when debugging as it is very useful. I think we could reused the .anchor dir for the .gitignored path.