Fix #106771: Selection offset in timeline when NLA track is offset

The selection (box select, click select...) had an offset when selecting keys in the timeline.
That was because the function to get the NLA mapping ignored the timeline.

Pull Request: https://projects.blender.org/blender/blender/pulls/106904

source/blender/editors/animation/anim_draw.c

@@ -233,7 +233,8 @@ AnimData *ANIM_nla_mapping_get(bAnimContext *ac, bAnimListElem *ale)
            ANIMCONT_DOPESHEET,
            ANIMCONT_FCURVES,
            ANIMCONT_NLA,
-           ANIMCONT_CHANNEL)) {
+           ANIMCONT_CHANNEL,
+           ANIMCONT_TIMELINE)) {
     /* handling depends on the type of animation-context we've got */
     if (ale) {
       /* NLA Control Curves occur on NLA strips,