Ported LoggingConfig from Python to Julia

[JawadAhmadCS]

This PR ports the LoggingConfig module from Python (Stingray) to Julia.
It provides a custom logging system with color-coded log levels.

Changes

• Added src/loggingconfig.jl for log handling.
• Updated src/stingray.jl to include LoggingConfig.
• Added test/test_logging.jl for testing logs.
• Modified test/runtests.jl to include logging tests.

Testing

• Logs are displayed with colors for different levels (Info, Warn, Error).
  
  

This contribution is part of my efforts for Google Summer of Code (GSoC) 2025 to work on Spectral Timing in Julia. Contributing to Stingray.jl helps me gain codebase familiarity and deepen my understanding for meaningful GSoC contributions.

[JawadAhmadCS]

@matteobachetti your review required! Please check

[matteobachetti]

@JawadAhmadCS the porting of these accessory libraries (logging, configuration, etc) is very low-priority, especially because the Python and Julia implementations are likely to require completely different mechanisms for each of them.