UI: Display an error message and disable salt actions when salt is unavailable

[JBWatenbergScality]

Component:

UI

Context:

Instead of login the user out in case of salt API unavailability, the user should be prompted with a message disclaiming it and be able to access monitoring screens. Salt related actions should be disabled.

Closes: #3117

[bert-e]

Hello jbwatenbergscality,

My role is to assist you with the merge of this
pull request. Please type @bert-e help to get information
on this process, or consult the user documentation.

Status report is not available.

[bert-e]

Conflict

There is a conflict between your branch improvement/ui-salt-error-management and the
destination branch development/2.8.

Please resolve the conflict on the feature branch (improvement/ui-salt-error-management).

 $ git fetch
 $ git checkout origin/improvement/ui-salt-error-management
 $ git merge origin/development/2.8
 $ # <intense conflict resolution>
 $ git commit
 $ git push origin HEAD:improvement/ui-salt-error-management

[bert-e]

Branches have diverged

This pull request's source branch improvement/ui-salt-error-management has diverged from
development/2.9 by more than 50 commits.

To avoid any integration risks, please re-synchronize them using one of the
following solutions:

• Merge origin/development/2.9 into improvement/ui-salt-error-management
• Rebase improvement/ui-salt-error-management onto origin/development/2.9

Note: If you choose to rebase, you may have to ask me to rebuild
integration branches using the reset command.