Java: Add support to Compact Source Files

[IdrissRio]

This PR adds support to compact source files (JEP 512).
It adds 2 new predicates Class.isImplicit and CompilationUnit.isCompactedSourceFile.

See internal PR for more info.

[Copilot]

Pull Request Overview

This PR adds support for Java 25 compact source files (JEP 512) by introducing two new predicates: Class.isImplicit() to identify implicitly declared classes and CompilationUnit.isCompactSourceFile() to identify compilation units containing compact source files.

• Added database schema support with new isImplicitClass table
• Implemented library predicates for detecting compact source files and implicit classes
• Created comprehensive test suite with multiple query examples

Reviewed Changes

Copilot reviewed 20 out of 21 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
java/ql/lib/config/semmlecode.dbscheme	Added isImplicitClass table definition for tracking implicit classes
java/ql/lib/semmle/code/java/Type.qll	Added Class.isImplicit() predicate to detect implicit classes
java/ql/lib/semmle/code/java/CompilationUnit.qll	Added CompilationUnit.isCompactSourceFile() predicate
java/ql/lib/upgrades/*/semmlecode.dbscheme	Database upgrade schema adding isImplicitClass table
java/ql/lib/upgrades/*/old.dbscheme	Previous database schema for comparison
java/downgrades/*/semmlecode.dbscheme	Database downgrade schema removing isImplicitClass table
java/downgrades/*/old.dbscheme	Previous schema for downgrade comparison
java/ql/test/library-tests/compact-source-files/*	Test files demonstrating compact source file functionality
java/ql/lib/change-notes/2025-07-23-compact-source-files.md	Release notes documenting the new feature

[geoffw0]

LGTM (when the internal PR is approved as well).

The base branch was changed.