fix: base url extraction in case its an object or string array

[Tomer-L]

the problem is that buildRedirectURL function can receive baseUrl of type 'object' (returned from the function getSingleSignOnService)

The “url” argument must be of type string. Received an instance of Object

I ran into this issue myself when integrating with jumpcloud as IDP, after some online research I found out this solution
https://community.n8n.io/t/n8n-enterprise-sso-configuration-jumpcloud/65861/11
Beside of the support for object type I added support for the case that baseUrl is []string since the function getAssertionConsumerService may return it

Tested and it solved my problem.

[Tomer-L]

This might fix: #405 #308 #328
CC @tngan