feat: provision to handle payment authorization event in server script for custom documents (#16712)

Currently, there is no provision to handle payment authorization events via server script. So it's not possible if a user wants to link payments against custom documents. 

Thus adding a provision in server script 
- Setup checkout for custom doc 
<img width="1299" alt="Screenshot 2022-03-11 at 2 44 19 PM" src="https://user-images.githubusercontent.com/3784093/157838010-989f6009-83d6-4329-92a6-bb2b6b38438b.png">

- Handle payment callback
<img width="1051" alt="Screenshot 2022-04-22 at 11 28 19 AM" src="https://user-images.githubusercontent.com/3784093/164612613-d321edb3-c7f8-4063-b809-8ae5fe46ee66.png">

## Documentation
https://frappeframework.com/docs/v13/user/en/desk/scripting/server-script/edit?wiki_page_patch=bbed0fcd9a

frappe/core/doctype/server_script/server_script.json

@@ -49,7 +49,7 @@
    "fieldname": "doctype_event",
    "fieldtype": "Select",
    "label": "DocType Event",
-   "options": "Before Insert\nBefore Validate\nBefore Save\nAfter Insert\nAfter Save\nBefore Submit\nAfter Submit\nBefore Cancel\nAfter Cancel\nBefore Delete\nAfter Delete\nBefore Save (Submitted Document)\nAfter Save (Submitted Document)"
+   "options": "Before Insert\nBefore Validate\nBefore Save\nAfter Save\nBefore Submit\nAfter Submit\nBefore Cancel\nAfter Cancel\nBefore Delete\nAfter Delete\nBefore Save (Submitted Document)\nAfter Save (Submitted Document)\nOn Payment Authorization"
   },
   {
    "depends_on": "eval:doc.script_type==='API'",
@@ -109,7 +109,7 @@
    "link_fieldname": "server_script"
   }
  ],
- "modified": "2022-04-07 19:41:23.178772",
+ "modified": "2022-04-22 11:24:01.151662",
  "modified_by": "Administrator",
  "module": "Core",
  "name": "Server Script",

frappe/core/doctype/server_script/server_script_utils.py

@@ -17,6 +17,7 @@ EVENT_MAP = {
 	"after_delete": "After Delete",
 	"before_update_after_submit": "Before Save (Submitted Document)",
 	"on_update_after_submit": "After Save (Submitted Document)",
+	"on_payment_authorized": "On Payment Authorization",
 }
 
 

frappe/utils/safe_exec.py

@@ -146,6 +146,7 @@ def get_safe_globals():
 			),
 			make_get_request=frappe.integrations.utils.make_get_request,
 			make_post_request=frappe.integrations.utils.make_post_request,
+			get_payment_gateway_controller=frappe.integrations.utils.get_payment_gateway_controller,
 			socketio_port=frappe.conf.socketio_port,
 			get_hooks=get_hooks,
 			enqueue=safe_enqueue,