feat: usethis tools

[gadenbuie]

Create tools around core usethis functions (not all). Please suggest functions you'd like to see implemented as tools here. Here's a starting list of tools that I think would be helpful and woldn't need too many guardrails

• create_package() (in current folder)
• use_package(), use_dev_package()
• use_r() and use_test()
• use_vignette() and use_article()
• use_author()
• use_license() (mit/gpl/agpl/lgpl/apache/cc0/ccby)
• use_build_ignore() and use_gitignore()
• use_testthat()
• use_pkgdown()
• use_news_md()
• use_readme_rmd()