Fix typos with codespell

Using codespell 2.2-dev from current git.

Added `misc/scripts/codespell.sh` to make it easier to run it once in a
while and update the skip and ignore lists.

(cherry picked from commit 1bdb82c64e)

scene/animation/animation_tree.cpp

@@ -1011,7 +1011,7 @@ void AnimationTree::_process_graph(float p_delta) {
 						TrackCacheAudio *t = static_cast<TrackCacheAudio *>(track);
 
 						if (seeked) {
-							//find whathever should be playing
+							//find whatever should be playing
 							int idx = a->track_find_key(i, time);
 							if (idx < 0) {
 								continue;