Feature/added litellm component (#4327)

* feat: add ChatLitellm component and LitellmApi credential

* fix: lint errors

* Update LLMFilterCompressionRetriever.ts

---------

Co-authored-by: Henry Heng <henryheng@flowiseai.com>

packages/components/credentials/LitellmApi.credential.ts

@@ -0,0 +1,23 @@
+import { INodeParams, INodeCredential } from '../src/Interface'
+
+class LitellmApi implements INodeCredential {
+    label: string
+    name: string
+    version: number
+    inputs: INodeParams[]
+
+    constructor() {
+        this.label = 'Litellm API'
+        this.name = 'litellmApi'
+        this.version = 1.0
+        this.inputs = [
+            {
+                label: 'API Key',
+                name: 'litellmApiKey',
+                type: 'password'
+            }
+        ]
+    }
+}
+
+module.exports = { credClass: LitellmApi }