add github actions for checking, styling, documenting, and spell checking

[iantaylor-NOAA]

What was changed/addressed

As noted in #38, there are currently no github actions for this repository. This PR adds github actions from {ghactions4r} to

• spell check the package, added by running ghactions4r::use_spell_check()
• run R CMD CHECK, added by running ghactions4r::use_r_cmd_check()
• run devtools::document() and styler::style_pkg(), added by running ghactions4r::use_doc_and_style_r()

I ran spelling::update_word_list() locally and only found one misspelled word.
I also ran styler::style_pkg() and it made a bunch of changes to whitespace but no significant changes to code format, which is also really impressive.

[iantaylor-NOAA]

I don't think any of these changes are controversial and all are easy to revise in the future (other than the whitespace cleanup), so I'm going to go ahead and merge them without further review.