New Refactoring: Add Braces to JSX Attribute

[nicoespeon]

Is this request related to a problem? Please describe.

Sometimes, I need to transform a primitive JSX attribute into an expression. To do so, I need to wrap the attribute with braces. I'd be nice if Abracadabra could do it for me.

Describe the solution you'd like

With following code:

function render() {
  return <Header title="Hello" />; 
}

If my cursor is on the title="Hello" attribute, I'd like to propose a quick fix to add braces around:

function render() {
  return <Header title={"Hello"} />; 
}

Additional context

The difference between these 2 snippets in terms of AST is a JSXExpressionContainer.

First AST is:

Second AST is:

So we need to put the value of the attribute into a JSXExpressionContainer if it's not already.

[nicoespeon]

Implemented in #70 that got merged. This refactoring will be shipped in the next release, thanks to @timvancleef 🎉