Add toggle group color indicators

[danielchalmers]

• introduce a reusablem JaToggleGroup component that minimally wraps MudToggleGroup and supports colored toggle selections with a leading vertical indicator bar so you can immediately know which is selected at a glance
• update DataPointView to replace MudToggleGroup with JaToggleGroup without changing any other code
• JaToggleGroup will only contain properties that are used by DataPointView. everything else is done internally
• isolate CSS to JaToggleGroup.razor.css
• use MAUI color APIs to automatically pick the hue/saturation for each toggle item, based on the source primary color. Derive the per-toggle colors from the theme’s primary color via hue shifts, applying them solely to the selected state and the vertical indicator so the indicator clearly reflects the chosen option.
• it must support an arbitrary amount of colors so it works with both the enum toggle types and the bools etc which have different number of items