Fix/embeded block

[ricardobrg]

Updates TIKI SDK JS to 2.1.2

• closes tiki/integrations#132

Updates the Liquid settings and the JavaScript code to create the Title, License and Payable

• closes tiki/integrations#122

Create the Customer Discount request and sign it with TIKI SDK IDP

• closes tiki/integrations#131

This is almost the final code for the embedded block. The final changes will be made in tiki/tiki-shopify#7.

What is missing:

• Update the discount settings to the variables saved in the backend (waiting on tiki/tiki-shopify#6 to use real data)
• Update the fetch function to use the Shopify proxy correctly (waiting on tiki/tiki-shopify#9)