[Azure OpenAI] Make credentials optional when env variables are set (#3418)

* Make Azure OpenAI credentials optional when env variables are set

* Add documentation for env vars

packages/components/nodes/llms/Azure OpenAI/AzureOpenAI.ts

@@ -5,6 +5,12 @@ import { ICommonObject, INode, INodeData, INodeOptionsValue, INodeParams } from
 import { getBaseClasses, getCredentialData, getCredentialParam } from '../../../src/utils'
 import { getModels, MODEL_TYPE } from '../../../src/modelLoader'
 
+const serverCredentialsExists =
+    !!process.env.AZURE_OPENAI_API_KEY &&
+    !!process.env.AZURE_OPENAI_API_INSTANCE_NAME &&
+    !!process.env.AZURE_OPENAI_API_DEPLOYMENT_NAME &&
+    !!process.env.AZURE_OPENAI_API_VERSION
+
 class AzureOpenAI_LLMs implements INode {
     label: string
     name: string
@@ -30,7 +36,8 @@ class AzureOpenAI_LLMs implements INode {
             label: 'Connect Credential',
             name: 'credential',
             type: 'credential',
-            credentialNames: ['azureOpenAIApi']
+            credentialNames: ['azureOpenAIApi'],
+            optional: serverCredentialsExists
         }
         this.inputs = [
             {