Update ibm-mq-metrics module to follow style guide

[Copilot]

This PR updates the ibm-mq-metrics module to follow all recommendations in the style guide, excluding the @nullable annotation section as requested.

Changes Made

Made public classes final: Updated 7 public non-internal classes to be final as required by the style guide:

• WmqContext - IBM MQ connection context class
• WmqMonitor - Main monitoring class
• QueueManager - Configuration class for queue manager settings
• ResourceFilters - Configuration class for resource filtering
• ExcludeFilters - Configuration class for exclude filters
• WmqUtil - Utility class for IBM MQ operations
• MessageBuddy - Utility class for PCF message handling

Improved static imports: Updated the MetricAssert test utility class to use static import for assertThat from AssertJ, following the style guide's recommendation for commonly used test methods.

Verification

• All existing tests continue to pass
• Code formatting compliance verified with spotlessCheck
• Full module build successful
• Changes are minimal and surgical (8 files changed, 11 insertions, 10 deletions)

The module was already largely compliant with the style guide - most test files already had proper static imports, class organization was correct, and no final parameters or local variables were found that needed removal.

Fixes #383.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.