Ability to tail be default with option to expand to full view

[ssbarnea]

Logs can often be quite long but in most cases the last lines are more important for the user. This is a required to allow one optional parameter which will enable a tailing option.

A pure-CSS only expand/collapse approach can be achieved using details/summary HTML5 elements, which are supported by most browsers.

To get an idea about how this feature would work take a look at https://zuul.opendev.org/t/openstack/build/738d31c679bf4609b921e42dddb3c666 -- look for "more/less" link on top of the logs section.

That feature request would not require changing any default behavior as it would only be triggered if an optional parameter is mentioned (the number of lines to tail).