Add debugging to the plugin

[Kira-Pilot]

Recently we have been investigating a hard-to-reproduce integrated terminal latency issue. We should introduce some logging and diagnostics into the plugin so we can provide a build to the affected user and glean more information:

• add centralized logger (if there isn't one already)
• add debug calls to thorny areas of code as identified in our walkthrough, as well as to lifecycle events
• provide user with a debug build

[bcpeinhardt]

There is a centralized logger, and a dedicated output channel for the extension which we write to. I think a further thing we could provide is a "Support.md" file, with instructions on what debugging/troubleshooting tools we provide and how to collect information for CS. Ideally any part of that process that can be scripted should be.