Add current section to playlist

[masaball]

Related issue: #6209

[cjcolvar]

I tested this out locally but I wasn't seeing a change in behavior but maybe I was testing it incorrectly or expecting behavior that is different than how it works.

Steps I took:

1. Create an item and upload 2 files
2. Edit the structure for the first file and add two divs with two spans under each div
3. On the view page select the first span under the first div
4. Click Add to playlist, select current section (Name of first div), and click Add
5. Go to playlist and see that all four spans have been added to the playlist (instead of the two under the first div)

Digging a little deeper maybe this is an issue with just the label displayed in the modal. I'm wondering if getTimelineScopes() is marking the wrong structure node as current-section. Maybe the HTML of the structure changed in ramp and that method didn't get updated? That's a guess.

[masaball]

Looking back at the ticket, I may have had too simple a structure on my test item as I'm not sure I had multiple divs.

Regardless, I was interpreting the current section option to be for adding an entire masterfile and then for adding just a subset of divs or spans you would use the current track option. If I have that behavior right, seeing all four spans in the playlist would be the expected behavior. So it would be that the modal just has the current-section label wrong. I'll take another look tomorrow at getting that populated properly.