.Net: Standardize name 'logger' across the project

[shawncal]

Description

Throughout the repo, we have a mix of logger and log (plus variations such as Log, _log) used to hold an ILogger instance.

This PR seeks to standardize the name logger, Logger and _logger to represent ILogger object references -- including properties and method parameters -- and Log as the method (action) that the logger can take.

To reviewers, this is a large and extraordinarily mundane PR with many identical substitutions. Please take a closer look at:

• IKernel.cs
• Kernel.cs
• SKContext.cs
  ...as these additionally contain Obsoleted properties.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄
  => This is a breaking change.