Migrate JavaParser-Based Expression Parsing to Javac API

[akulk022]

This pull request introduces a complete replacement of the JavaParser-based expression parsing pipeline in JavaExpressionParseUtil with an implementation based on the standard javac API (com.sun.source.tree.*).

A brief overview of the updated implementation details:

1. Adding utility support via JavacParseUtil to programmatically parse string expressions into com.sun.source.tree.ExpressionTree nodes.
2. Implementing ExpressionTreeToJavaExpressionVisitor, a visitor that mirrors the logic of the original ExpressionToJavaExpressionVisitor.
3. Handling all expression cases such as identifiers, literals, method invocations, field accesses, binary operations, and class literals using javac's AST.

Unit testing was successful on the new changes by running JavaExpressionCheckerTest and the overall framework tests.