Gender neutral user interface

[ChristophWurst]

Describe the task

To help translators translate user interface into more neutral terms, we want to replace a few terms in the source/English strings.

1. User/users -> person/account
2. Participants/attendees -> people

Ref https://help.nextcloud.com/t/geschlechtsneutrale-sprache-genderneutral/82200/107

Affected components

• Calendar
• Calendar Resource Management
• Contacts
• Mail

To do

• Find the old terms
• Replace them