Adds Optional dims arg for subsetting by dimensions when plotting a multidimensional model (#1955)

* adds optional dims arg to contributions_over_time method

* adds test_contributions_over_time_with_dim for testing new dim arg

* adds optional dims arg to plot.budget_allocation method

* adds test_budget_allocation_with_dims for testing new dims arg for plot.budget_allocation method

* adds examples for plot.budget_allocation and plot.contributions_over_time methods for dims arg

* adds _validate_dims helper function

* adds a more clear ValueError data -> idata

* contributions_over_time - allow dims argument subsetting by a list of desired values

* adds extra tests for contributions_over_time

* budget_allocation - allow dims argument subsetting by a list of desired values

* adds initial test_budget_allocation_with_dims_list test

* adds _dim_list_handler helper function

* updates methods to use _dim_list_handler()

* saturation_scatterplot - allow dims argument subsetting by a list of desired values

* adds new tests for dims list in TestSaturationScatterplotDims

* adds tests for new helper functions _validate_dims and _dim_list_handler

* fixing tests

* saturation_curves - allow dims argument subsetting by a list of desired values

* adds TestSaturationScatterplotDims for new dims arg to saturation_curves

* updates tests in TestSaturationCurvesDims

* updates tests in TestSaturationCurvesDims

* updates multi-scenario plotting block with dims used in budget_allocation()

* updates multidimensional example with dims as an optional arg for plotting

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Co-authored-by: Juan Orduz <[email protected]>

Author: timbo112711