Revert "fix: only sign executables (ocaml#8361)"

This reverts commit ade58ac.

bin/install_uninstall.ml

@@ -336,7 +336,7 @@ module File_ops_real (W : sig
     =
     let chmod = if executable then fun _ -> 0o755 else fun _ -> 0o644 in
     match (special_file : Special_file.t option) with
-    | None -> Artifact_substitution.copy_file ~conf ~executable ~src ~dst ~chmod ()
+    | None -> Artifact_substitution.copy_file ~conf ~src ~dst ~chmod ()
     | Some sf ->
       let ic, oc = Io.setup_copy ~chmod ~src ~dst () in
       Fiber.finalize

src/dune_rules/artifact_substitution.ml

@@ -673,15 +673,7 @@ let replace_if_different ~delete_dst_if_it_is_a_directory ~src ~dst =
   if not up_to_date then Path.rename src dst
 ;;
 
-let copy_file
-  ~conf
-  ?(executable = false)
-  ?chmod
-  ?(delete_dst_if_it_is_a_directory = false)
-  ~src
-  ~dst
-  ()
-  =
+let copy_file ~conf ?chmod ?(delete_dst_if_it_is_a_directory = false) ~src ~dst () =
   (* We create a temporary file in the same directory to ensure it's on the same
      partition as [dst] (otherwise, [Path.rename temp_file dst] won't work). The
      prefix ".#" is used because Dune ignores such files and so creating this
@@ -696,11 +688,7 @@ let copy_file
       let open Fiber.O in
       Path.parent dst |> Option.iter ~f:Path.mkdir_p;
       let* has_subst = copy_file_non_atomic ~conf ?chmod ~src ~dst:temp_file () in
-      let+ () =
-        if executable
-        then Conf.run_sign_hook conf ~has_subst temp_file
-        else Fiber.return ()
-      in
+      let+ () = Conf.run_sign_hook conf ~has_subst temp_file in
       replace_if_different ~delete_dst_if_it_is_a_directory ~src:temp_file ~dst)
     ~finally:(fun () ->
       Path.unlink_no_err temp_file;

src/dune_rules/artifact_substitution.mli

@@ -53,7 +53,6 @@ val decode : string -> t option
     and then atomically renamed to [dst]. *)
 val copy_file
   :  conf:Conf.t
-  -> ?executable:bool
   -> ?chmod:(int -> int)
   -> ?delete_dst_if_it_is_a_directory:bool
   -> src:Path.t