/progress/chapter matrix: sticky headers

[smadbe]

Motivation

In the progress matrix, when there are many users, it is required to scroll. However, as columns match content, it is difficult to keep track what column is for what content:

Test with that content as the usual user: https://dev.algorea.org/en/a/1980584647557587953;p=;pa=0/progress/chapter?watchedGroupId=917454091139548680

Acceptance criteria

• Use stickly header in this matrix so that the headers with content name is still visible when scrolling down the page