Add HTTP Collector Plugin for Endpoint Monitoring

[s0nny78]

Summary

• Implement HTTP endpoint health checking plugin for compliance monitoring
• Support for configurable HTTP requests with authentication and validation
• Creates OSCAL-compliant evidence for audit trails

Features

• HTTP Methods: GET, POST, PUT, DELETE support
• Authentication: Basic auth with username/password
• Validation: Status code checking (200-299 = success) and regex pattern matching
• Configuration: Timeout, custom headers, certificate validation control
• Evidence: Rich OSCAL evidence with activities, subjects, and properties

Test Configuration

Includes test configuration with three scenarios:

• JSON endpoint with regex validation
• Simple status check endpoint
• Basic authentication endpoint

Files Added

• plugins/http-collector/main.go - Plugin implementation
• plugins/http-collector/test-config.yaml - Test configuration
• Updated .gitignore to exclude plugin binaries

Testing

• ✅ Successfully tested with live endpoints
• ✅ Evidence creation confirmed via API
• ✅ UI integration verified