PY-72210 DataView: improve speed of get_value_occurrences_count

1. Split additional computation for statistics and computation for visualizations
2. Computation for visualization is now called only by request

GitOrigin-RevId: d872fbd9ed5732633814228713acc734ee2043e5

python/pydevSrc/src/com/jetbrains/python/tables/TableCommandType.kt

@@ -4,5 +4,8 @@ import com.intellij.openapi.util.IntellijInternalApi
 
 @IntellijInternalApi
 enum class TableCommandType {
-  DF_INFO, SLICE, DF_DESCRIBE
+  DF_INFO,
+  SLICE,
+  DF_DESCRIBE,
+  VISUALIZATION_DATA
 }