added check for baseline stream in for live line plotting

[whs92]

Description

The only change I have made is to add an if statement which checks whether the stream that is to be plotted has name baseline if it does, no new plot is made.

Motivation and Context

Aiming to solve problem where if a run is performed which contains baseline and primary (and maybe other plans) we don't really want to plot the baseline measurement. This can contain a lot of readings (=lines) that we don't really want to see in the plot

How Has This Been Tested?

I have only tested this by loading the widget using Jupyter and creating a run which has baseline and primary streams. I initially attempted to create a test in the pytests file but found that I couldn't use the build_simple_run function which was used in those tests because it only has one stream. The RunBuilder() would work, but I couldn't work out how to add incremeneting scan_id