GDPR: Document the new JavaScript tracker methods: requireConsent, rememberConsentGiven, forgetConsentGiven, setConsentGiven

[mattab]

In this guide https://developer.matomo.org/api-reference/tracking-javascript
we want to list the new methods: requireConsent, rememberConsentGiven, forgetConsentGiven, setConsentGiven

that were added in #12558
and are documented in https://developer.matomo.org/guides/tracking-javascript-guide#asking-for-consent

[mattab]

Done here: https://developer.matomo.org/api-reference/tracking-javascript#managing-consent