Rename EXTRACT_QUOTES to EXTRACT_UNQUOTE

Whenever I see EXTRACT_QUOTES, I'm always confused whether it means to
leave the quotes in or to take them out. Let's say "unquote", like we
say "cunescape".

src/shared/conf-parser.c

@@ -758,7 +758,7 @@ int config_parse_strv(
         for (;;) {
                 char *word = NULL;
 
-                r = extract_first_word(&rvalue, &word, NULL, EXTRACT_QUOTES|EXTRACT_RETAIN_ESCAPE);
+                r = extract_first_word(&rvalue, &word, NULL, EXTRACT_UNQUOTE|EXTRACT_RETAIN_ESCAPE);
                 if (r == 0)
                         break;
                 if (r == -ENOMEM)