Adds a safe check, i18n is expecting undefined not null. Fix a method name and translation to be at placeholder.

Removing translateString forces using data-i18n attributes, to make sure we do not forget to set them. Missing data-i18n attributes is a problem with late loading where we can end up without translation, without text. Missing data-i18n attributes is also problem that strings will not be translated when changing language.
Fixes a bug in invite dialog, where remove password button was shown for non moderators.

Enable ESLint on jitsi-meet with the same configuration and the same
goals as in lib-jitsi-meet.

This reverts commit 93648f361b.