Histogram: Adds histogram test dashboard & test data (#34821)

* Added test data that contains normal distribution

* Added histogram test dashboard

* Fixed so panels share same data

public/app/plugins/datasource/testdata/components/CSVFileEditor.tsx

@@ -12,6 +12,7 @@ export const CSVFileEditor = ({ onChange, query }: EditorProps) => {
     'population_by_state.csv',
     'gdp_per_capita.csv',
     'js_libraries.csv',
+    'weight_height.csv',
     'browser_marketshare.csv',
   ].map((name) => ({ label: name, value: name }));