feat(n8nApi node): add core node for consuming the n8n API (#4076)

* feat(n8n node): create n8n core node for consuming the n8n API

Co-authored-by: Michael Kret <michael.k@radency.com>

packages/nodes-base/credentials/N8nApi.credentials.ts

@@ -0,0 +1,43 @@
+import {
+	IAuthenticateGeneric,
+	ICredentialTestRequest,
+	ICredentialType,
+	INodeProperties,
+} from 'n8n-workflow';
+
+export class N8nApi implements ICredentialType {
+	name = 'n8nApi';
+	displayName = 'n8n API';
+	documentationUrl = 'n8nApi';
+	properties: INodeProperties[] = [
+		{
+			displayName: 'API Key',
+			name: 'apiKey',
+			type: 'string',
+			default: '',
+			description: 'The API key for the n8n instance',
+		},
+		{
+			displayName: 'Base URL',
+			name: 'baseUrl',
+			type: 'string',
+			default: '',
+			placeholder: 'https://<name>.app.n8n.cloud/api/v1',
+			description: 'The API URL of the n8n instance',
+		},
+	];
+	authenticate: IAuthenticateGeneric = {
+		type: 'generic',
+		properties: {
+			headers: {
+				'X-N8N-API-KEY': '={{ $credentials.apiKey }}',
+			},
+		},
+	};
+	test: ICredentialTestRequest = {
+		request: {
+			baseURL: '={{ $credentials.baseUrl }}',
+			url: '/workflows?limit=5',
+		},
+	};
+}