JFG-783 Change line - legend relation in all plots

+ creating PlotSeriesDto object , that represent single plot, from one place for metric and plots.
+ MetricDto do not contain superfluous PlotDatasetDto that represent same values from MetricDto.values in other way.
+ create legend tree.
- plots rendering in old way
- new legend tree presents in  panel bellow plot
propose to rename to LegendNode and don't make it generic => less universal, but more clear