basic/escape: add helper for quoting command lines

src/basic/escape.h

@@ -68,3 +68,4 @@ char* escape_non_printable_full(const char *str, size_t console_width, XEscapeFl
 
 char* shell_escape(const char *s, const char *bad);
 char* shell_maybe_quote(const char *s, ShellEscapeFlags flags);
+char* quote_command_line(char **argv);