Address boolean attributes when passing them to the store

The following discussion from !27658 (merged) should be addressed:

• @ohoral started a discussion: (+6 comments)

  this one as confusing, cause in case config.isAdmin is false, config.isAdmin !== undefined === true. Is it correct? Why do we check for undefined?

This happens because a 'boolean' attribute is represented in haml and html without any 'value' examples can be: disabled or readonly

In the dataset these elements are represented like so {disabled: ''} or {disabled: null} ( depending on browser) and so the only way to ascertain if they are truthy is to do disabled !== undefined which is ugly and prone to confusion

OPTIONS:

• 🅰 use lodash isNil => disabled = !isNil(dataset.disabled)
• 🅱 leave it as it is
• 🆎 in the haml force the attributes to be disabled="true"
• 🔤 write a parsing function that takes a 'dataset schema' and a dataset and parse them
• 🏀 Put data in a <template type="application/json"> outside the root element (thanks @xanf)!

I would like to move on with 🔤 we could mirror 1:1 what vue does when a prop is defined and we could also get rid of JSON.parse and similar shenanigans