Bug fix: support 'line' elements in kWaveArray plotting

[stellaprins]

What does this PR do?
This PR adds support for plotting line elements in the plotArray method of the kWaveArray class. Previously, attempting to plot a line element resulted in an error due to unsupported element type. The new code handles the 'line' case.

It can be tested with the following code:

karray=kWaveArray;
karray.addLineElement([1,1,1], [2,3,4]);
karray.plotArray;

This should result in the following Figure:

I also checked plotting for other accepted dimensional inputs for start_point and end_point, i.e. 1D: [x], 2D: [x, y].

Fixes #4 Bug: kWaveArray support for plotting line elements 🐛

Notes
Note that the CI is working! 🎉

[stellaprins]

Oops! I accidentally deleted this branch while cleaning up some old and merged ones, opening it again.