Update styling commands to work similarly across systems

[brookslogan]

styler::style_pkg() appears to be inconsistent about formatting vignettes. I've tried on my system with CRAN and GitHub versions of styler, and they don't seem to format the vignettes, and CI complains about that. [I just needed to start a new session after upgrading styler.]

[brookslogan]

Since CI seems to be running off of the GitHub version, this means that we need to update the dev dependency installation to use that version rather than CRAN. Maybe install.packages("devtools") + devtools::install_dev_deps().

[brookslogan]

Might be worth a line in the README explaining this sort of situation; if CI complains about styling it suggests that the dev needs to upgrade to latest CRAN styler and style_pkg() in a fresh session.

[brookslogan]

Also might note that styling should be followed by redocument()ing, as the styler can change example code, and those changes should be propagated to the Rd files.

[dshemetov]

I added a couple CI actions to automatically handle these chores:

• document
• style

We also have the Makefile command make chores which will execute these commands in the right order.