[electrophysiology_browser] Incorrect/missing translations

[lapadulamichael]

Describe the bug
A clear and concise description of what the bug is

• Site, Project and Output type are missing DB translations for every language (Site and Project not shown in screenshot but opening dropdown shows missing translations).
• In sessions, Channel Types is not translated
• In a session while on French, Next is being translated as La prochaine étape a commencé (should be Suivant)
• Missing translations while adding event
• Wrong translation for Open Dataset Tag Manager, should be Gestionnaire de balises de jeux de données
  To Reproduce
  Steps to reproduce the behavior (attach screenshots if applicable):

1. Go to 'electrophysiology_browser'
2. See Project, Site and Output type. See missing translations
3. Click on a 'raw' link
4. See other previously mentioned incorrect translations