Add option to Nunjucks macro to activate the JavaScript enhancement

[romaricpascal]

What

Add an option to the Nunjucks macro to control the rendering of data-module="govuk-file-upload" (not rendering by default).

Add options for controlling the different translation strings used by the JavaScript component.

Why

Because once enhanced with JavaScript, the component displays on a much taller area than the native <input>, we've decided to use a feature flag to trigger its use. People using the HTML can set the data-module="govuk-file-upload" manually. An option in the Nunjucks macro will provide a clear API for doing that in Nunjucks, and to be consistent with the other components, options to control the translations should be made available in Nunjucks.

Who needs to work on this

Developers

Who needs to review this

Developers

Done when

• The File Upload's macro has an option to control whether JavaScript component will execute
• The File Upload's macro has options to control the translation strings for the JavaScript component