Fix runtime log level changes

[seanmil]

Describe the change

The console and stream handlers currently do not respect runtime logger instance-level log level configuration changes as they store the instance-level log level which was set when they were initialized.

Why are we doing this?

To permit dynamic log level changes to work as documented: https://github.com/piotrmurach/tty-logger/blob/master/README.md#24-configuration

Benefits

• Fix documented behavior to work as documented.
• Permit greater flexibility in working with changing log levels.

Drawbacks

I did not measure it, but this change likely results in a small performance hit as there is some additional logic run for every log message.

Requirements

• Tests written & passing locally?
• Code style checked? Unsure what to do here - no Rubocop in project and the latest version reports a great many errors.
• Rebased with master branch?
• Documentation updated? Unneeded - fixes behavior to match documentation.
• Changelog updated?