fix(reactor): Retain externally referenced resource resolver types

[YagUber]

Fixes invalid output when a .NET Reactor resource resolver type is still used by application code.

When resource decryption and method inlining were enabled, de4dot always removed the detected resource-resolver type. The sample I came across retained externally callable resolver helpers, and other module types still reference those methods after deobfuscation. Removing the resolver type leaves a dangling method reference and causes dnlib to reject the output while writing method bodies.

Now before removing the resolver type, scan methods outside that type for calls to resolver methods other than its initializer and retain the type when an external reference remains.

[meck-gd]

Thanks!