Idea: generate .gitattributes

[Atry]

According to https://docs.github.com/en/repositories/working-with-files/managing-files/customizing-how-changed-files-appear-on-github , .gitattributes file can be used to tell GitHub a file is generated and the changes to the files will be hidden by default in pull requests. It would be nice if we also generate an entry in .gitattributes for each generated file