Handle null/undefined values for params

[devlikepro]

Right now when we set null/undefined in any params (likely get) - it returns the string "null/undefined"

• Eg. Error 404 even with APP configured n8n-nodes-chatwoot#10
• This is likely why: https://community.n8n.io/t/null-and-undefined-in-string-fields/31060/3

We need to handle that case somehow.

We could

1. Handle null/undefined with some params
2. Add a flag for each optional field, like "Include Field"
   need to research the best way how to fix it