Provide possiblity to use custom AI endpoint for assistent description

[de-jcup]

Situation

With #3709 we have automated the descriptions, but the MITRE descriptions will not be 100% clear for users and the description could be more user friendly.

Wanted

As a user I want an easy to read description of a finding inside the SecHub report.

Solution

It shall be possible to configure and use an API endpoint which provides

• Provide configuration possibility for an AI endpoint
  (via communication templates from Introduce communication templates #3712)
• API endpoint will be called with cached Mitre information details
  (from Provide MITRE descriptions by assistent description for report #3709), cwe-id, language etc.
• Provide integration test (mocked ai call)
• Provide wire mock test (simulate AI REST endpoint)
• The information shall be cached
• Document