shared: extract edit-util from systemctl-edit

src/shared/edit-util.h

@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "path-lookup.h"
+
+typedef struct EditFile {
+        char *path;
+        char *tmp;
+        unsigned line;
+} EditFile;
+
+void edit_file_free_all(EditFile **ef);
+
+int create_edit_temp_file(
+                const char *new_path,
+                const char *original_path,
+                char ** const original_unit_paths,
+                const char *marker_start,
+                const char *marker_end,
+                char **ret_tmp_fn,
+                unsigned *ret_edit_line);
+
+int run_editor(const EditFile *files);
+
+int trim_edit_markers(const char *path, const char *marker_start, const char *marker_end);