feat: add a way to reject cookies with Cookiebar

[bfabio]

• Document preference cookie name saved by the cookiebar
• Make the cookie expire after 6 months
• Add a close and a reject button in the example, as per guidelines, and their data attribute (data-close="cookiebar).
• Update the example with the new message

• [x] Le modifiche sono conformi alle linee guida di design.
• [x] Il codice è coerente con le indicazioni di progetto.
• [ ] Le modifiche sono state verificate sui Browser supportati e per diverse risoluzioni dello schermo.
• [ ] Sono stati effettuati test di accessibilità in ottemperanza a quanto descritto nell'area "Accessibilità" delle linee guida di design.
• [x] La documentazione è stata aggiornata.

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[Fupete]

@gpeirolo please check the a11y of this updated component markup, eg. keyboard interactions... cc @cfabry

[gpeirolo]

@Fupete the markup is correct and keyboard interaction works fine (tabbing and moving with arrows to buttons and links).

Screen reader experience presents some problems:

• the dialog is not announced when the page is loaded (aria-live seems to be ineffective, perhaps because its content is already there)
• the "x" character is read as "per" (should be hidden with aria-hidden)
• the user must navigate the entire page to get to the cookiebar

Further review by @cfabry is advisable.

[Fupete]

@gpeirolo indeed it is. I ping @cfabry also on slack in a moment.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[bfabio]

@stale mind your business

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[bfabio]

@stale :-1:

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[Fupete]

nope @stale tx

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Name	Status	Preview	Updated
bootstrap-italia	✅ Ready (Inspect)	Visit Preview	Jan 11, 2023 at 9:07PM (UTC)

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.