feat: Data transformation nodes and actions in Nodes Panel (#7760)

- Split Items List node into separate nodes per action
- Review node descriptions
- New icons
- New sections in subcategories

---------

Co-authored-by: Giulio Andreini <andreini@netseven.it>
Co-authored-by: Deborah <deborah@starfallprojects.co.uk>
Co-authored-by: Michael Kret <michael.k@radency.com>

packages/nodes-base/nodes/DateTime/DateTime.node.json

@@ -23,6 +23,6 @@
 		]
 	},
 	"subcategories": {
-		"Core Nodes": ["Helpers", "Data Transformation"]
+		"Core Nodes": ["Data Transformation"]
 	}
 }

packages/nodes-base/nodes/DateTime/V2/DateTimeV2.node.ts

@@ -31,6 +31,7 @@ export class DateTimeV2 implements INodeType {
 			},
 			inputs: ['main'],
 			outputs: ['main'],
+			description: 'Manipulate date and time values',
 			properties: [
 				{
 					displayName: 'Operation',