Refactor XMLTokener.unescapeEntity() to reduce complexity

Extracted hex and decimal parsing logic into separate methods to
address SonarQube complexity warning:
- parseHexEntity(): handles ઼ format
- parseDecimalEntity(): handles { format

This reduces cyclomatic complexity while maintaining identical
functionality and all validation checks.

.gitignore

@@ -16,3 +16,6 @@ build
 /gradlew
 /gradlew.bat
 .gitmodules
+
+# ignore compiled class files
+*.class