Remove anything deprecated for 1.0 release

[jgabry]

Just opening this so I can add it to the v1.0.0 milestone. There are many deprecated arguments we should remove in v1.0.0. (Alternatively, since we're still in beta we could just remove them in a future beta release since we've already done several beta releases keeping the deprecated arguments.)

[jgabry]

Once #520 is merged we'll also need to remove support for using old .cmdstanr directory instead of .cmdstan. Removing this would entail removing the old argument to cmdstan_default_path() and cmdstan_default_install_path and removing the use of cmdstan_default_path(old = TRUE) from zzz.R and from set_cmdstan_path().