Add offline data information in the header

Tested with success

Verified cases:

• the header contains a number of pending offline events based on the number of cached stock events created by a user in the local storage

• after click “Pending offline events(..)” link, the user is moved to the Pending offline events page not available from the Navigation bar

• number of pending offline events refreshes after adding a new offline event by the user

Verified on:

• Ubuntu 20.04 OS

• Google Chrome Version 85.0.4183.83

• Firefox Version 80.0

During working on the ticket, it was decided that the text ‘Check connection' should be on the same line as ‘You are offline’. Information about Pending offline events should be on the line below. It was also decided that we will use the name 'Pending offline events' and not 'Pending offline operations'
Summarizing the offline header should look like this:

The number of events is the number of events that have been created by the user who is currently logged in.
If there are no stock events in local storage or there are events only for other users (other than the current user), there should be no message about Pending offline events in the offline header.

Redirection to the table with pending offline events was implemented as part of the ticket OLMIS-7198