Feature/scihub 1247 enable mentioning users

[zgrybus]

Changes

• Added mentions plugin that provides functionality for transforming @Abc to Abc
• Stop rendering link, when we use space while typing

Screenshot / Video of the changes

Pre-Merge Checklist

Notifications:

• [x] Added Reviewers

Documentation:

• [x] Updated CHANGELOG.
• [ ] Updated version.

Code Quality

• [ ] Added or updated unit tests.