* Migrate ILSpy.AddIn.VS2022 to SDK-style VSIX project
* Retire the legacy VS2017/2019 ILSpy add-in
* Build the VS extension via dotnet build on the slnx
* Inline ILSpy.AddIn.Shared into ILSpy.AddIn.VS2022
* Restore the VS add-in menus broken by the SDK-style migration
https://github.com/icsharpcode/ILSpy/issues/694
Supports methods, enums, delegates, properties, interfaces, events and classes.
TODO: disambiguate overloaded methods by number and type of parameters
Changes (only) to ILSpy.AddIn project:
add: code window context menu item "Open code in ILSpy"
add: OpenCodeItemInILSpyCallback does the work, using Visual Studio code model to interrogate source at selection point
change: add additional argument support to OpenAssemblyInILSpy (to support "/navigateTo")