Add GetLogLevel method to Logger source file

[cmaynard-ngwpc]

The GetLogLevel method was declared in the Logger.hpp file but not defined in the Logger.cpp file.

Additions

• Added GetLogLevel method definition in Logger source file

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests