Update extension to support asynchronous autoloading

[marazt]

Update extension to support asynchronous autoloading.

https://docs.microsoft.com/en-us/visualstudio/extensibility/synchronously-autoloaded-extensions?view=vs-2019

[avalanchis]

Just updated to Visual Studio 2019 Version 16.2.2 and ConfigTransformation will no longer run.

"This extension was not loaded because it uses deprecated synchronous autoload APIs."

[kcddagger]

The reporting bar should also have a link with the option to Allow Synchronous Autoloading.

However this would only be recommended as a temporary solution. I agree with @marazt that an update to the extension to utilize asynchronous autoloading would be in the best interests of everyone who uses this extension.