Reimplement treetable without using primeng

[fateeand]

Primeng treetable is implemented in such a way that it requires a lot of ugly workarounds to adjust it.

Virtual scroller doesn't work as expected out of the box and the biggest issue is that it doesn't support autolayout for scrollable tables (header and body are separated into different tables by design - temporary workaround is implemented in #276, but we still can't prevent flickering and sometimes cells width match is still not accurate).