Revert "Add .gitattributes and .gitignore to skip SF-related files."

This reverts commit c8994f07f576972a896e34862fb171660a10cb45.
Revert "Revert "Add .gitattributes and .gitignore to skip SF-related files.""

This reverts commit 41032b0dc13253ccc450572824401a533ca93b11.