add option to ignore failed connections

[David-Aires]

🚀 Merge Request: Implement Filtering for Failed Connections

Summary

This update introduces the FilterFailedConnections flag to allow filtering of failed connection attempts (conn_state = 'S0').
The changes ensure that such entries are excluded when the flag is enabled, improving data relevance and reducing noise in analysis.

Changes

• ✅ Added FilterFailedConnections config option
• ✅ Updated filtering logic in config/filter.go
• ✅ Modified importer/conn.go to apply the new filter
• ✅ Updated unit tests in config_test.go and filter_test.go
• ✅ Added integration test in integration/filter_test.go

Testing & Validation

• ✅ Unit tests validate the correct application of the FilterFailedConnections flag.
• ✅ Integration test confirms that connection entries with conn_state = 'S0' are properly filtered out when the flag is enabled.
• ✅ Configuration updates were verified in default_config.hjson.

Impact & Risks

• ⚠️ No breaking changes; default behavior remains unchanged (FilterFailedConnections: false).
• ⚠️ If enabled, failed connections will no longer be included in analysis, which could affect visibility into failed connection attempts.

Next Steps

• 📌 Consider extending filtering options for additional connection states if needed.

Relates to #29