Resize visualisations in expanded mode

Expected behaviour

When a visualisation is expanded, it should take up most of the available area, not just the lower half.

Current behaviour

The visualisation content only takes up the lower portion of the screen.

Steps to reproduce

1. Click on expand on any visualisation.
2. The area used is not expansive.

Environment

Error logs (if available)

Possible solution

Use relative heights for the visualisation wrapper and add listeners to Vega charts to adjust the height.

QA Steps

[To be completed by Coko once dev is done]

Scheduling