After a Polyglot Notebooks release, `dotnet-interactive` tool is not updated until VS Code is restarted

[jonsequitur]

Since it became possible to restart extensions without restarting VS Code, the possibility has emerged for a Polyglot Notebooks extension update to cause the extension to get out of sync with the expected dotnet-interactive tool version. The VS Code Restart extensions action is currently not sufficient to download the latest version of the tool.

The tool versions check needs to be changed so that it checks on extension restart.