Сustom Widgets and Tabs

• Support widgets order for include_widgets parameter
• Support an ability to add a custom widget to Tabs with include_widgets parameter
• Moved options to a separate module
• Added options to specify statistical tests for DataDrift and TargetDrift Dashboards:
  stattest_func - to set a custom statistical test for all the features
  feature_stattest_func - to set a custom statistical tests for each individual feature
  cat_target_stattest_func - to set a custom statistical test for categorical target
  num_target_stattest_func - to set a custom statistical test for numerical target
• Refactored Widgets and Tabs for simpler customisation