[freeflow][test] Transfer lid-driven cavity test to an example

Ghia 1982 provide reference solutions (plot over line data) for the lid-driven cavity test.

I have used the data in my thesis and we could maybe also add them to the test.

• Turn the test into an example
• Add literature reference data
• Use plotoverline script from bin to extract line data
• Use scipy/gnuplot to plot and compare with the reference data