move questions init function to questions.js

[hugosolar]

Description

This PR changes the way to initialize questions on this plugin. Questions.start()

Technical details

The function was initialized in the markup of the WordPress shortcode. Regardless the fact of this is not a good practice it seems to be called before jquery was included.
I move the init function to questions.js which make more sense and we ensure the execution of the function once jquery is included

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• I added tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no
  visible errors.

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