Update sticky header so that I can manage content at the very bottom of the studio pages

User Story

As a course author, I want the sidebar actions to appear to the right of the course content even for the very bottom course elements on the course outline and unit pages in studio, so I can use the studio sidebar to manage the content in my course without having to scroll up (even for that very last element at the bottom of the page).

Acceptance Criteria

Given I am a course author on the Course Outline page in studio for a course that has enough sections, subsections, and units that I need to scroll down to view them all
When I view the last element at the very bottom of the page
Then I am able to use the sidebar to view the info, add tags, manage settings, etc without having to scroll up to view or use the studio sidebar

AND

Given I am a course author on the Unit page in studio for a course that has enough components that I need to scroll down to view them all
When I view the last component at the very bottom of the page
Then I am able to use the sidebar to view the info, add tags, manage settings, etc without having to scroll up to view or use the studio sidebar

Notes

See: this comment for context.

Start by reading the Course Outline and Unit page implementations for the sticky studio sidebar, then review the linked comment for context. Reproduce the issue with long course content and inspect the sidebar behavior at the final outline element and unit component. Done means the sidebar actions remain usable without scrolling up on both pages.