options, command: simplify some option updates

Remove wrapper properties for OSD and video position updates, use the
new mechanism for them. We can mark the options directly. Update
behavior will work for more options (since I've casually marked more
affected options than the old less direct mechanism covered).

sub/osd.c

@@ -81,6 +81,7 @@ const struct m_sub_options osd_style_conf = {
         .align_x = -1,
         .align_y = -1,
     },
+    .change_flags = UPDATE_OSD,
 };
 
 const struct m_sub_options sub_style_conf = {
@@ -99,6 +100,7 @@ const struct m_sub_options sub_style_conf = {
         .align_x = 0,
         .align_y = 1,
     },
+    .change_flags = UPDATE_OSD,
 };
 
 static bool osd_res_equals(struct mp_osd_res a, struct mp_osd_res b)