vcs: Restructure vcs module

Just like writing and qutebrowser modules, restructured the version
control software module to make more use of dotter's ability to
precisely link files. All contained programs have a top-level directory
and all the files that correspond to that specific software lie beneath
in the directory tree.

.dotter/global.toml

@@ -15,6 +15,10 @@ sh = "~"
 
 [vcs.files]
 "vcs/README.md" = { target = "~/NOWHERE", type = "symbolic", if = "false" }
+"vcs/git" = "~/.config"
+"vcs/jj" = "~/.config/jj"
+"vcs/gitignore/config" = "~/.config"
+"vcs/gitignore/local" = "~/.local"
 vcs = "~"
 
 [nvim.files]