Implement expandable rows ("row accordion")

[ivan-aksamentov]

As a part of the experiment with persistent informational widgets (#83), we would like to try to add table rows a capability to expand.

That is, on trigger, each row would expand down, exposing underlying details section. This is similar to bootstrap's accordion widget: https://getbootstrap.com/docs/4.3/components/collapse/#accordion-example

Each row would have a place where user clicks to trigger the expansion: could add a dedicated button with a chevron or just trigger when clicking on sequence name in the table.

We can allow (or not) for multiple open rows at the same time.