changes from main

[dvovk]

Changes:

• Added functionality to display download metrics such as size, total time, and average rate.
• Improved command for diagnostic stages and avoided printing empty tables.
• Implemented a diagnostics database for saving state data.
• Replaced the speed test library with a custom version using Erigon's infrastructure.
• Limited speed test runs and stopped tests upon snapshot download completion.
• Fixed issues with downloaded percentages exceeding 100% and JSON unmarshalling errors. Improved error messages for better debugging.
• Continued listening for events even after initial completion, considering the two-part download process.
• Refactored stages to include substages and enhanced logging for header chain downloads.
• Bug Fixes
• Fixed race conditions in test cases and improved diagnostics test client.
• Optimized database writes, reduced unnecessary warnings, and adjusted log levels.
• Refactored mutex usage for network peers and other critical sections.