Is your feature request related to a problem? Please describe.

An addon can contain appModules, brailleDisplayDrivers, synthDrivers, globalPlugins and visionEnhancementProviders. However, there is no way for addons to store code that has to be shared between packages. Imagine a case where a constant has to be defined that has to be available in both an appModule and a globalPlugin. I'm pretty sure @josephsl might know of other cases like this.
In my case, I want to store a base class subclassing driverHandler.Driver that will be a base of both a synthDriver and brailleDisplayDriver.

Describe the solution you'd like

I'd like to suggest the possibility for addons to provide code for the following NVDA packages:

• comInterfaces: for addons requiring com interface definitions that can be resolved with comTypes automatically (i.e. without doing a magic import trick to make the comInterface available to comtypes)
• utils: package that can hold classes and modules that ought to be shared between plugins in the addon

Cc @josephsl and other addon contributors