Add support for Annotation Processors in the Javac Extension

[PiIsRational]

Changes

Extended the Javac Extension to be able to load annotation processors, while the java code is getting checked
in KeY. This includes creating settings for the Javac Extension, to be able to set the checkers.
Also, the there are changes to the run step of the gradle script
to add (add-export and add-opens) directives to the java runtime such that annotations processors can access the internal java compiler data structures.
This is required to be done by hand when using KeY as a jar and would require the following (or similar) command:

java \
    --add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
    --add-exports jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED \
    --add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
    --add-exports jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED \
    --add-exports jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED \
    --add-exports jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED \
    --add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
    --add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED \
    --add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED \
    -jar key-2.12.4-dev-exe.jar

Type of pull request

• New feature (non-breaking change which adds functionality)
• There are changes to the (Java) code
• There are changes to the deployment/CI infrastructure (gradle, github, ...)

Ensuring quality

• I made sure that introduced/changed code is well documented (javadoc and inline comments).
• I have tested the feature as follows:
  • I used it with multiple annotation processors
  • I loaded KeY with various settings to check if and when they are deleted
• I have checked that runtime performance has not deteriorated.

Additional information and contact(s)

@WolframPfeifer is involved in this pull request.

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

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 50.34%. Comparing base (ba0945c) to head (3f01c36).
⚠️ Report is 90 commits behind head on main.

Files with missing lines	Patch %	Lines
...n/java/de/uka/ilkd/key/settings/Configuration.java	0.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3686      +/-   ##
============================================
+ Coverage     47.99%   50.34%   +2.35%     
+ Complexity    16045    15902     -143     
============================================
  Files          1683     1597      -86     
  Lines         96053    91028    -5025     
  Branches      15390    14555     -835     
============================================
- Hits          46097    45825     -272     
+ Misses        44683    39989    -4694     
+ Partials       5273     5214      -59     

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[wadoon]

One solution to the exports-problem is to start javac in an external process. This means:

1. Writing a main function inside KeY
2. On call, use the current classpath and JRE, and start a new Java process which enters the new main function.
3. Capture the diagnostics in the new process, and send them in a structured way to stdout.
4. Read the stdout in the process spawner.

[WolframPfeifer]

Thanks for this PR, which will allow running Checker Framework checkers (e.g. for Nullness of Ownership) from the KeY GUI directly.

Also, thanks to @wadoon for the initial draft of the external checker, and @PiIsRational for polishing.

I have a few minor complaints about the use of var. When these are fixed, the PR would be ready from my point of view. Also, there is code smell in the unit test (check without assert), but we could also keep it like that.

[WolframPfeifer]

In my opinion, it is a bit of a code smell to have a test without any asserts (was already the case for the original test of this class). However, this can still count as some kind of smoke test, so I do not let it block the merge ...

[PiIsRational]

Why is the listener needed here? It seems to only be used to generate an error message for a corner case (a system without a Java compiler). Would it make sense to therefore remove it?