Fix data alignment issues in get_data() in AudioStreamSample

I am fixing the issue by adding DATA_PAD to the return pointer as
suggested by hi-ogawa

When using set_data in AudioStreamSample in PoolByteArray, the data is set
using a DATA_PAD to pad the pointer to the correct place as such

uint8_t *dataptr = (uint8_t *)data;
copymem(dataptr + DATA_PAD, r.ptr(), datalen);
data_bytes = datalen;
godot/scene/resources/audio_stream_sample.cpp#L473

All I am doing is adding a DATA_PAD to the return pointer to
get_data() in AudioStreamSample to change

godot/scene/resources/audio_stream_sample.cpp#L48
PoolVector<uint8_t>::Write w = pv.write();
copymem(w.ptr(), data, data_bytes);

to

PoolVector<uint8_t>::Write w = pv.write();
uint8_t *dataptr = (uint8_t *)data;
copymem(w.ptr(), dataptr + DATA_PAD, data_bytes);

Please review whether or not set or get is correct.
Because this issue seems to be fixable by removing DATA_PAD in set_data()
instead of adding DATA_PAD to get_data(). I have not tested the latter
fix

Fixes #issue, 11873

scene/resources/audio_stream_sample.cpp

@@ -486,7 +486,8 @@ PoolVector<uint8_t> AudioStreamSample::get_data() const {
 		{
 
 			PoolVector<uint8_t>::Write w = pv.write();
-			copymem(w.ptr(), data, data_bytes);
+			uint8_t *dataptr = (uint8_t *)data;
+			copymem(w.ptr(), dataptr + DATA_PAD, data_bytes);
 		}
 	}