Investigate and handle vulnerabilities from security scan

Description

There are many vulnerabilities in the SAST (see here for example) which should be investigated and possibly fixed. Especially the critical ones. Also check if there is an option to mark false positives to be ignored in future scans.

Investigated Vulnerabilities

• Deferring unsafe method "Close" on type "*os.File" in nucleus/principalNetworkDomain.go:604 -> Solution
• Improper Neutralization of Argument Delimiters in a Command in controller_test.go:40 -> Unchanged, because it's just a test case and the request can not get changed from outside. Linked rule
• Improper Neutralization of Argument Delimiters in a Command in controller_test.go:48 -> Unchanged, because it's just a test case and the request can not get changed from outside. Linked rule
• Improper Neutralization of Argument Delimiters in a Command in http_test.go:49 -> Unchanged, because it's just a test case and the request can not get changed from outside. Linked rule
• Potential file inclusion via variable in nucleus/principalNetworkDomain.go:600 -> Solution

Addressed missing error handling

• config/config.go:38
• northbound/server/core.go:102
• nucleus/principalNetworkDomain.go:613
• nucleus/principalNetworkDomain.go:618
• cli/cmd/init.go:76
• cli/cmd/prompt.go:89
• csbi/run.go:59