use_github_action() should .Rbuildignore the entire .github folder

[DavisVaughan]

Right now, when I use use_github_actions_tidy() I end up with this in .Rbuildignore:

^\.github/workflows/R-CMD-check\.yaml$
^\.github/workflows/pr-commands\.yaml$

If I run devtools::build() I'll get these empty directory notes:

> devtools::build()
✔  checking for file ‘/Users/davis/Desktop/r/packages/hardhat/DESCRIPTION’ ...
─  preparing ‘hardhat’: (885ms)
✔  checking DESCRIPTION meta-information ...
─  installing the package to process help pages
✔  creating vignettes (5.8s)
─  checking for LF line-endings in source and make files and shell scripts (400ms)
─  checking for empty or unneeded directories
   Removed empty directory ‘hardhat/.github/workflows’
   Removed empty directory ‘hardhat/.github’
─  building ‘hardhat_0.0.0.9001.tar.gz’

Should use_github_action() just add ^\.github$ to `.Rbuildignore?

[jennybc]

There are several functions that write into .github/ so it's probably time to add a helper that does the right/better thing for all of them.

[hadley]

@jimhester fixed this recently