LLM support in KeY UI

[wadoon]

Synopsis

PR brings LLM prompt integration into KeY. Using the API of the KIT service (openai-compat).

Intended Change & Plan

• MVP

  • Minimal working prompt

    

  • Adding files from the Java model
    UI w/o functionality
    

  • Adding current sequent

  • DnD support for formulas.

• Second level
  • Get list of models
  • DnD from source view?
  • Generation of computation trace from Schwörers thesis?
  • Prompts
  • Background knowledge
• Third level
  • Integration into dialogs (invariant, contract)

Type of pull request

• New feature (non-breaking change which adds functionality)
• There are changes to the (Java) code

Ensuring quality

• User documentation: https://keyproject.github.io/key-docs/user/LLM/
• I made sure that introduced/changed code is well documented (javadoc and inline comments).
• I made sure that new/changed end-user features are well documented (https://github.com/KeYProject/key-docs).
• I added new test case(s) for new functionality.
• I have tested the feature as follows: ...
• I have checked that runtime performance has not deteriorated.
• For new Gradle modules: I added the Gradle module to the test matrix in
  .github/workflows/tests.yml

The contributions within this pull request are licensed under GPLv2 (only) for inclusion in KeY.