Show user when issue tracker is not working

[Sebastiaan127001]

Is your feature request related to a problem? Please describe.
Recently, in one of the Quality-time instances, the issue tracker did not work due to the fact that the API-manager could not connect to the internet. The end user gets no warning at all. Moreover, when going to the issue tracker configuration, everything appeared to be fine. Upon trying to create an issue by clicking the button in a technical debt tab of a metric, nothing happened. After a long time, a toaster message finally appeared with no valuable message.

Describe the solution you'd like
When the issue tracker does not work, this should be communicated early to the end user. For instance when viewing the config of the create new issue button should be disabled.

You can reprodude / test this by disabling the api-manager's connection to the internet while the issue tracker is hosted on the internet.

Additional context