refactor(demo): Language list, optional/mandatory knobs, fixing the notes plugin - FRONT-925

[planctus]

PR description

WARNING!!! it contains an update of the storybook-addon-notes plugin, take care.

These are changes that were lost from a previous pr where i probably forgot to push the right file, these changes are fixing also the output in the notes of components like social media share and language list where we give the possibility the delete item by unsetting them through the knobs.
The output in the notes tab if you choose "none" as the label of an item should be clean, the item is removed from the demo and the include code doesn't contain the item.
The same happens also in the social mendia components, if you remove an icon the item is removed as well and in the notes tab the output of the include code should be clean.

QA Checklist

In order to ensure a safe and quick review, please check that your PR follow those guidelines:

• I have put the vanilla component as devDependencies
• I have put the specs package as devDependencies
• I have added the components directly used in the twig file (with include or embed) as dependencies
• My component is listed in @ecl-twig/ec-components's dependencies
• My variables naming follow the guidelines (snake case for twig)
• I have provided tests
• I have provided documentation (for the "notes" tab)
• If my local yarn.lock contains changes, I have committed it
• I have given my PR the proper label (pr: review needed to indicate that I'm done and now waiting for a review ,pr: wip to indicate that I'm actively working on it ...)

[papegaill]

Everything is correctly working on my side, notes correctly updated as expected. O k for language list knobs too.