i18n: fix plurals

[carlinmack]

Package version (if known): All

Describe the bug

A clear and concise description of what the bug is.

Across Invenio we have many places where we have a "count noun" form where we want the noun to respect the count. For example, "1 result" and "2 results".

Tasks

• Fix translation with count in Python
• Fix translation with count in Javascript
• Find all instances where this should be fixed across the modules
• Fix all instances
• Correct the documentation
  • See https://www.i18next.com/translation-function/plurals

Related

#2162

[carlinmack]

Created issue from leftover task in #2895

[carlinmack]

I assume that it the solution would also get rid of this avalanche in the console when developing locally