Add A Expand All/Collapse All Button For Content Column

[michaelcilibrasi]

Describe the problem to be solved
Expanding and collapsing text in an annoying feature in Redocly. Sometimes users want them all opened, or all closed, For instance, the browser-based search feature (think Chrome), works best if everything is expanded. After that, then be able to collapse them as it makes scrolling easier.

Describe the solution you'd like
Include an expand all/collapse all button for the content column.

Describe alternatives you've considered
Given them being either all expanded or all collapsed, we choose to have them all expanded. That makes searches easier, not navigation. We've also tried writing our own JavaScript but the way it's built makes this very difficult. Either way, the clients do a lot of expanding and collapsing.