web: collapse sections by default

[nicks]

If you have a lot of resources, tilt let's you group them by label.

By default, all groups are expanded. But presumably if you added labels, it's because the resource list is getting unwieldy! Let's try collapsing by default and see if people complain.

https://github.com/tilt-dev/tilt/issues/6201

[nicks]

@lizzthabet curious how this dovetails with other "organizing containers" work you've been doing.

[nicks]

we talked about this a bit today. we're concerned that the current 'collapse' UI doesn't really give much indication to new users what to do or what parts of the interface are important.

thinking about introducing some new "default" state that is more compact, but gives a stronger indication of what's happening.