Add translation on Publik authentification button

[luciegrau]

Describe the need

As an admin, if Publik is enabled on the platform, I want to be able to change the translation of the log in button via the term customizer. I already try to use the available translations but not of them has been successful:

[Bertille-M]

@luciegrau est-ce qu'on peut le passer en done ?