refactor: move non-symbols to defs.h headers

src/nvim/ex_cmds.h

@@ -1,35 +1,6 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
-#include "nvim/eval/typval_defs.h"
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: export
-#include "nvim/os/time_defs.h"
-#include "nvim/pos_defs.h"  // IWYU pragma: keep
-
-/// flags for do_ecmd()
-enum {
-  ECMD_HIDE       = 0x01,  ///< don't free the current buffer
-  ECMD_SET_HELP   = 0x02,  ///< set b_help flag of (new) buffer before opening file
-  ECMD_OLDBUF     = 0x04,  ///< use existing buffer if it exists
-  ECMD_FORCEIT    = 0x08,  ///< ! used in Ex command
-  ECMD_ADDBUF     = 0x10,  ///< don't edit, just add to buffer list
-  ECMD_ALTBUF     = 0x20,  ///< like ECMD_ADDBUF and set the alternate file
-  ECMD_NOWINENTER = 0x40,  ///< do not trigger BufWinEnter
-};
-
-/// for lnum argument in do_ecmd()
-enum {
-  ECMD_LASTL = 0,   ///< use last position in loaded file
-  ECMD_LAST  = -1,  ///< use last position in all files
-  ECMD_ONE   = 1,   ///< use first line
-};
-
-/// Previous :substitute replacement string definition
-typedef struct {
-  char *sub;            ///< Previous replacement string.
-  Timestamp timestamp;  ///< Time when it was last set.
-  list_T *additional_elements;  ///< Additional data left from ShaDa file.
-} SubReplacementString;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "ex_cmds.h.generated.h"