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/undo.c

@@ -99,6 +99,7 @@
 #include "nvim/quickfix.h"
 #include "nvim/screen.h"
 #include "nvim/sha256.h"
+#include "nvim/state.h"
 #include "nvim/strings.h"
 #include "nvim/types.h"
 #include "nvim/os/os.h"