Integrate prom controller with UI

[vladimirvivien]

Fixes #59

This pull request introduces significant enhancements to the ktop application, focusing on integrating hybrid metrics support, improving configuration management, and enhancing the user interface for metrics visualization. Key changes include the addition of hybrid metrics support, a new configuration system, and updates to the display logic to reflect metrics source health and trends.

Hybrid Metrics Support:

• Hybrid Metrics Controller Integration: Added a hybrid metrics controller to enable dynamic switching between Prometheus and Kubernetes metrics-server based on availability and health. This includes fallback mechanisms and periodic health checks. (cmd/ktop.go [1] k8s/client.go [2] [3]

Configuration Management:

• New Configuration System: Introduced config/metrics_config.go to manage metrics-related settings, including source type, Prometheus-specific options, and display preferences. Default configurations are provided, and users can override settings via a YAML file or command-line flags. (config/metrics_config.go [1] cmd/ktop.go [2] [3]
• Example Configuration File: Added example-config.yaml to demonstrate configuration options and structure for users. (example-config.yaml example-config.yamlR1-R69)

Display Enhancements:

• Dynamic Header Updates: Updated the application header to reflect the health and state of the metrics source dynamically, with color-coded indicators for better visualization. (application/app_ctrl.go [1] [2]
• Periodic Refresh of UI: Implemented a periodic refresh mechanism to ensure metrics and health indicators are up-to-date. (application/app_ctrl.go application/app_ctrl.goR188-R203)

These changes collectively improve the flexibility, usability, and reliability of the ktop application for monitoring Kubernetes clusters.