refactor: eliminate misc2.c

move `call_shell` to misc1.c
Move some fns to state.c
Move some fns to option.c
Move some fns to memline.c
Move `vim_chdir*` fns to file_search.c
Move some fns to new module, bytes.c
Move some fns to fileio.c

src/nvim/digraph.c

@@ -17,7 +17,6 @@
 #include "nvim/getchar.h"
 #include "nvim/mbyte.h"
 #include "nvim/message.h"
-#include "nvim/misc2.h"
 #include "nvim/memory.h"
 #include "nvim/garray.h"
 #include "nvim/normal.h"