ENH: Introduction of basic i18n (internationalization).

Summary

1. Add basic i18n support to Components "UserComponent" and "LoginForm".
2. Fix some minor issues with both components

Focus

• a lot of the changes are just of the form <string> to t(<string>). t is the translation functions
• Docs for the i18n library: https://react.i18next.com/

Test Environment

• Run mock server with npm run mock
• Test in action with caosdb/customers/aba/server-profile!1

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• Reference related issues
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• Appropriate user and developer documentation (or not necessary)
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