mill init should produce .ignore files

[GoogeTan]

I think mill init should produce .ignore and .gitignore files if they are absent in the directory. They should contain /out/ and /.bsp/ directories. The user will need them anyway so this will improve user experience.

If a user opens newly created project they will see dozens of files from out directory which is a bit confusing.

[lefou]

Although git is a quite ubiquitous VCS nowadays, it's not a given it's what the user uses. So creating that file could be a un-feature for some users. Once we create that file, there likely comes a follow-up feature request that wants a way to disable it. We either make it configurable from the beginning (cli option) or instead show a hint for the user to create it manually.

[GoogeTan]

Then the command might ask if user needs them or not in an interactive way. In case a user need automatically call the command(e.g. from script) the user can pass those answers as arguments

[bherw]

What if mill init detected if .git exists, and appends to .gitignore if it does? Then it shouldn't annoy anyone.