[FIX] Importers not recovering when an error occurs

Improve how the importer progress gets sent to the client and change the structure of the importers imports

[FIX] Csv importer: work with more problematic data

This way, it will re-import old imports just fine.
For new imports, the order of timestamps in the CSV files will have to
be  the same, always. So, either using the same dumps or enforcing order
on the CSV dump is required.

Interface clean up, with users&channels being allowed to be empty for
CSV import.

Otherwise two messages that received the same timestamp in the same room
will break the import.

Makes more sense for testing purposes, or when there are other reasons to
import data separately or in blocks.

* Add ESLint rule `prefer-template`

* Add ESLint rule `template-curly-spacing `

* ESLint ignore rocketchat-livechat/assets/rocket-livechat.js

* Add ecmascript package to all packages

* Use ecmascript package for server and client on saml package

* Fix compilation