player: fix inconsistent AO pause state in certain situations

Pause can be changed during a file change, such as with for example
--reset-on-next-file=pause, or in hooks, or by being quick, and in this
case the AO's pause state was not updated correctly. mpctx->ao_chain is
only set if playback is fully initialized, while the AO itself in
mpctx->ao can be reused across files.

Fix this by always running set_pause_state() if the pause option is
changed. Could cause new bugs since running this used to be explicitly
avoided outside of the loaded state. The handling of time_frame is
potentially worrisome.

Regression due to recent audio refactor; before that, the AO didn't have
a separate/persistent pause state.

Fixes: #8079

player/command.c

@@ -6493,13 +6493,8 @@ void mp_option_change_callback(void *ctx, struct m_config_option *co, int flags,
         }
     }
 
-    if (opt_ptr == &opts->pause) {
-        if (mpctx->playback_initialized) {
-            int val = opts->pause;
-            opts->pause = !val; // temporary hack to force update
-            set_pause_state(mpctx, val);
-        }
-    }
+    if (opt_ptr == &opts->pause)
+        set_pause_state(mpctx, opts->pause);
 
     if (opt_ptr == &opts->audio_delay) {
         if (mpctx->ao_chain) {

player/playloop.c

@@ -159,7 +159,7 @@ void set_pause_state(struct MPContext *mpctx, bool user_pause)
     if (internal_paused != mpctx->paused) {
         mpctx->paused = internal_paused;
 
-        if (mpctx->ao && mpctx->ao_chain)
+        if (mpctx->ao)
             ao_set_paused(mpctx->ao, internal_paused);
 
         if (mpctx->video_out)