[TEST] Splunk Interface Error Check

[georgedias]

Description of Test
The Splunk URL was added to Heimdall's Content Security Policy (CSP) as an allowed domain.
This is accomplished by providing the SPLUNK_HOST_URL .env variable where Heimdall allows cross-domain connection to the spluck host.

Additional testing needs to be conduct for proper error handling and notification to the user in the splunk connection.
(libs\hdf-converters\src\utils\splunk-tools.ts).