add pr on usethis for interaction functions

[maxheld83]

turns out these functions would better exist only in usethis in the first place.
among other reasons, this avoids having to rebuild functions that are unexported from usethis.

• [x] browse_workflow() as per add browse to main.workflow on github actions #72
• edit_workflow() as per add edit workflow function #51
• browse_ghactions() as per add browse_github_actions() #17

[maxheld83]

pending as per r-lib/usethis#629