Display warning if explorer is stuck for 2.2.4 - Closes #74

[MichalTuleja]

What was the problem?

• User should see instantly if there is something wrong with explorer, we can use some effect on header for that (red background, red blinking height, etc.).

How did I fix it?

• Added function that registers events for web-sockets and displays the corresponding background and message, depending on the event.

How to test it?

• Checked on chrome.

Review checklist

• The PR solves Display warning if explorer is stuck #74
• All new code is covered with unit tests
• All new code was formatted with Prettier
• Linting passes
• Tests pass
• Commit messages follow the
  commit guidelines
• Documentation has been added/updated