Feature: Collect contact information from users inside the chatbot

[0xi4o]

• Adds a leads tab to chatflow configuration
  
• Adds a dialog that lists all the leads captured
  

Related: FlowiseAI/FlowiseChatEmbed#119

[0xi4o]

@HenryHengZJ ready for review

[HenryHengZJ]

we mentioned to disable text box field when lead form is not yet filled:

[0xi4o]

Fixed the issues @HenryHengZJ

[titogarrido]

My lead calls are always pointing to localhost:3000, but I am using a custom hostname. How can I change the config to point /api/v1/leads to the right hostname? Thanks!