Improve UX when connectivity to Sonatype IQ Server becomes invalid

[madpah]

Currently if the configured IQ Server is unreachable, there is no friendly messaging to the user explaining the issue - just a white screen... ...this could be much much better

Scenarios to Handle

• Extension is fully configured, but connectivity to Sonatype IQ Server is broken:
  • No connection can be established
  • Connection can be established but unexpected (non-401) error response returned
• Component Evaluation returns 200 with and error:

{
    "submittedDate": "2023-08-10T08:31:58.700Z",
    "evaluationDate": "2023-08-10T08:31:58.701Z",
    "applicationId": "370bf138ffa0429791b7c269cd8edbb9",
    "results": [],
    "isError": true,
    "errorMessage": "The hostname for the Sonatype Data Services could not be resolved, please verify the network configuration (DNS) at the site where the Nexus IQ Server is operated (ID a427c55fa2014bed)"
}

• Credentials which are already configured in SPBE are changed in Sonatype IQ Server - this currently results in blank screen and no messaging. #102

FYI @maurycupitt