Support plotting multiple responses or set a limit to the number of series plotted

[hnformentin]

Describe the bug
When QCing the results of the run of a config file, I try to load many plots in Plot Viewer (in this case 14).
Black boxes and empty plots are returned, but no warning is raised about the max number of plots available.

To Reproduce
Steps to reproduce the behavior:

1. Open an ert config with webviz-ert
2. Select two ensembles
3. Select multiple responses

Expected behavior
I would expect to have all plots correctly plot or, if not possible, an warning and a limit of the number of plots possible to plot.

Screenshots

Desktop (please complete the following information):

• rgs node
• komodo 2022.09.03-py38