i18n(it): translate docs/guides/backend/google-firebase.mdx (#4196)

* i18n(it): partial translated docs/guides/backend/google-firebase.mdx (line 620)

* i18n(it): finished translation for docs/guides/backend/google-firebase.mdx

* fix(i18n/it): links

* i18n(it): added missing translation

* i18n(it): fix some transaltion error in docs/guides/backend/google-firebase.mdx

* i18n(it): translate docs/guides/backend/google-firebase.mdx

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Co-authored-by: vclemenzi <vclemenzi@users.noreply.github.com>
Co-authored-by: Yan Thomas <61414485+Yan-Thomas@users.noreply.github.com>