On the Margins of Employment, in the Centre of the Pandemic: Experiences of Unprotection and Social Vulnerability in the Great Lockdown [En Marge de L’emploi, Au Centre de la Pandémie: Expériences de Non-Protection Et de Vulnérabilité Sociale Durant Le Grand Confinement] [Nas Margens do Emprego, No Centro da Pandemia: Experiências de Desproteção e Vulnerabilidade Social No Grande Confinamento]