detect/analyzer: Extend analyzer with ICMP icode

[jlucovsky]

Continuation of #13445

Extend engine analysis output with ICMP icode information.

Link to ticket: https://redmine.openinfosecfoundation.org/issues/6359

Describe changes:

• Add utilitity function to JSONify U8 types
• Add icode value to analyzer output

Updates:

• Fix casting issue.

Provide values to any of the below to override the defaults.

• To use a Suricata-Verify or Suricata-Update pull request, link to the pull request in the respective _BRANCH variable.
• Leave unused overrides blank or remove.

SV_REPO= SV_BRANCH=https://github.com/OISF/suricata-verify/pull/2572 SU_REPO= SU_BRANCH=