Nicer error message for parse errors

[FliegendeWurst]

Intended Change

3406 leads to user-facing ParseCancellationExceptions, which are not debuggable. This PR enhances the user experience by actually showing the error in the context of the input file, and listing the found token and the expected token types. Previously, only the class name of the exception was displayed.

Type of pull request

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] Refactoring (behaviour should not change or only minimally change)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] There are changes to the (Java) code
• [ ] There are changes to the taclet rule base
• [ ] There are changes to the deployment/CI infrastructure (gradle, github, ...)
• [ ] Other:

Ensuring quality

• [ ] 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).
• [x] I added new test case(s) for new functionality.
• [x] I have tested the feature as follows: I tested the error reporting using the file below
• [ ] I have checked that runtime performance has not deteriorated.

missing_semicolon.key

\rules {
   missingSemicolon {
      \find(0=0)
      \replacewith(1=1)
  }
}

\problem { 0=0 }

Additional information and contact(s)

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

[codecov[bot]]

Codecov Report

Attention: 11 lines in your changes are missing coverage. Please review.

Comparison is base (1fb0c10) 37.77% compared to head (4d3b3ad) 37.78%.

Files	Patch %	Lines
...main/java/de/uka/ilkd/key/util/ExceptionTools.java	72.50%	9 Missing and 2 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #3417 +/- ## ============================================ + Coverage 37.77% 37.78% +0.01% - Complexity 17031 17037 +6 ============================================ Files 2076 2076 Lines 126950 126992 +42 Branches 21381 21387 +6 ============================================ + Hits 47952 47981 +29 - Misses 73092 73102 +10 - Partials 5906 5909 +3 ```

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[MarcoScaletta]

\rules { wrongTypeSchemaVar { \schemaVar update x, x2; \find(0=0) \replacewith(1=1) }; }

\problem { true }

[FliegendeWurst]

I added another case that handles your problematic input.