Script report for purchase analytics (#15612)

* Purchase Analytics Query Report

* Minor Changes

* Codacy Issue Fixes

* Codacy Issues Fixed

* Code cleaning and optimization

* Indentation Issue Fix

* Code cleaning and better function naming

* Added link for purchase analytics in buying.py

* Added link for production analytics in manufacturing.py

* Commonified purchase-analytics using Analytics class

* Codacy issue fix

erpnext/config/buying.py

@@ -122,10 +122,10 @@ def get_data():
 			"icon": "fa fa-table",
 			"items": [
 				{
-					"type": "page",
-					"name": "purchase-analytics",
-					"label": _("Purchase Analytics"),
-					"icon": "fa fa-bar-chart",
+					"type": "report",
+					"is_query_report": True,
+					"name": "Purchase Analytics",
+					"doctype": "Purchase Order"
 				},
 				{
 					"type": "report",