feat(anim_timeline): add repeat and more

[zipeartnes]

Description of the feature or fix

Added lv_anim_timeline_set_repeat_count function to allow for repeating and looping an animation timeline.
Added lv_anim_timeline_set_repeat_delay function to allow for delay repeating and looping an animation timeline.

Added lv_anim_timeline_get_repeat_count function to allow for getting the animation timeline repeat count.
Added lv_anim_timeline_get_repeat_delay function to allow for getting the animation timeline delay.

Notes

• Update the Documentation if needed.
• Add Examples if relevant.
• Add Tests if applicable.
• If you added new options to lv_conf_template.h run lv_conf_internal_gen.py and update Kconfig.
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[kisvegabor]

Hi,

These seem like quite reasonable changes. In order to merge this PR, please add some tests too.