Implement self-updating

NOTE: Need to create an installation experience first! See #10

DO NOT IMPLEMENT SELF-UPDATING FOR A GIVEN PLATFORM UNTIL ARTIFACT SIGNING IS COMPLETE FOR THAT PLATFORM

The CLI should detect and self-update to the latest version, similar to logic implemented in https://github.com/DamianEdwards/dotnet-dev-certs-plus/pull/4 adjusted appropriately for this CLI including:

• The source for updates are the releases on this repo (including the rolling dev release) Not nuget.org
• The CLI has its version embedded in it so it can be checked against the available versions to see if a newer one is available
• The logic should use the latest stable version of the NuGet.Versioning package to do version comparison logic
• The CLI will need a way to actually install the update here because it's a standalone executable, e.g. kusto update --check to check for updates, kusto update to install an update. At this point we will NOT implement automatic self-updating, rather automatic checking will take place (like the referenced PR) and when one is available a yellow message will be printed in the output of every other command.
• After downloading a new version, it should be checked to ensure the SHA256 of its contents matches what's recorded in the GH release for that asset
• The actual update command will need to properly handle updating the executable while it's running, e.g. rename current file to release lock before copying over new file

Review issue #10 for the installation experience and confirm artifact signing requirements before starting. Then study the referenced dotnet-dev-certs-plus pull request and the NuGet.Versioning approach, along with this repository's GitHub release assets. Done means stable and rolling releases can be checked, SHA256-verified, reported, and installed through the specified update commands without implementing automatic updating.