feat(core): Add "Client Credentials" grant type to OAuth2 (#3489)

* ⚡ Add OAuth2 client credentials grant type

* ⚡ Improvements

* 🐛 Fix linting issue

* 🐛 Fix typo

* 🐛 Fix small issue with type

* 🐛 When token expire get a new one instead of refreshing it

* ⚡ Fix issue that it did not display it correctly for OAuth1

Co-authored-by: Jan Oberhauser <jan.oberhauser@gmail.com>

packages/nodes-base/credentials/ServiceNowOAuth2Api.credentials.ts

@@ -19,6 +19,12 @@ export class ServiceNowOAuth2Api implements ICredentialType {
 			hint: 'The subdomain can be extracted from the URL. If the URL is: https://dev99890.service-now.com the subdomain is dev99890',
 			required: true,
 		},
+		{
+			displayName: 'Grant Type',
+			name: 'grantType',
+			type: 'hidden',
+			default: 'authorizationCode',
+		},
 		{
 			displayName: 'Authorization URL',
 			name: 'authUrl',