editors/vim: Flavorize and update to 8.2.3394

This commit completely rewires the vim ports. It includes the following:

* `vim' is now a TUI-only package. It is what the `vim-console' port
  was.

* `vim-gtk3' includes the TUI binary (vim) and a GTk3-backed GUI. It is
  what the `vim' port was.

* Each GUI toolkit has a separate package. There is vim-gtk3, -gtk2,
  -motif, -athena, and -x11.

* `vim-tiny' is still the same thing, except it includes a defaults.vim
  stub to silence a startup error message.

* Only the python3 language binding is included by default. Perl, Ruby,
  TCL, Scheme, and Lua can still be enabled via options. But there are
  very, very few plugins that require anything other than python.

* py27 support is removed entirely.

* CScope support is unconditionally enabled, but vim no longer depends
  upon it. If cscope is installed, it'll be used.

* The default ctags is now the version included in base. It's very
  rudimentary, but only a subset of users use ctags at all. Universal or
  exuberant ctags can still be enabled via option knobs.