Modernize Switch Statements with JDK 21 Patterns

[UrbanBobek]

Refactor legacy switch statements throughout Phoebus codebase to use JDK 21 modern switch expressions and pattern matching. Improve code readability and take advantage of exhaustiveness checking.

• Identify switch statements that can benefit from JDK 21 pattern matching
• Convert traditional switch statements to switch expressions where appropriate
• Use pattern matching for instanceof checks in switch cases
• Ensure exhaustiveness checking is leveraged
• Add tests to verify behavior remains unchanged

Resources:

• JDK 21 Pattern Matching: https://openjdk.org/jeps/441
• Switch Pattern Matching: https://docs.oracle.com/en/java/javase/21/language/pattern-matching.html