Add marshallers for GeneratedComInterface-based types

[jkoritzinsky]

• Add the marshallers defined in [API Proposal]: Define parameter marshalling of interfaces #85797 (fixes [API Proposal]: Define parameter marshalling of interfaces #85797)
• Add default marshalling rules for GeneratedComInterface-attributed types.
• Allow [MarshalAs(UnmanagedType.Interface)] on all types. If the type has the GeneratedComInterface attribute, then the object will be marshalled as that COM interface. Otherwise it will be marshalled as IUnknown* for whatever managed object wrapper is returned from a default-constructed StrategyBasedComWrappers instance.
  • If we want, we can limit this to types with [GeneratedComInterface] or [GeneratedComClass] or the object type. This may be more restrictive than required (an abstract base type of a [GeneratedComClass] type would be reasonable to have in a parameter list and would be expensive to reliably detect), but we could design some simple rules to limit invalid usage.

Some of the integration tests are disabled due to the following issue:

Since CreateObjectFlags.Unwrap will unwrap any Managed Object Wrapper from any ComWrappers instance, we can easily get into a bad state if a COM object is implemented by ComWrappers under the hood. Our tests capture this pretty well as the "native" side is loaded into a separate ALC, so the tests fail as the underlying managed object cannot be cast to the interface on the "managed" side of the test. We need to determine a solution for this problem and enable those tests before we merge in this work. We will resolve this problem by changing the behavior of CreateObjectFlags.Unwrap to be ComWrappers-specific. This change is specified in #86189

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Issue Details

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• Add the marshallers defined in [API Proposal]: Define parameter marshalling of interfaces #85797 (fixes [API Proposal]: Define parameter marshalling of interfaces #85797)
• Add default marshalling rules for GeneratedComInterface-attributed types.
• Allow [MarshalAs(UnmanagedType.Interface)] on all types. If the type has the GeneratedComInterface attribute, then the object will be marshalled as that COM interface. Otherwise it will be marshalled as IUnknown* for whatever managed object wrapper is returned from a default-constructed StrategyBasedComWrappers instance.
  • If we want, we can limit this to types with [GeneratedComInterface] or [GeneratedComClass] or the object type. This may be more restrictive than required (an abstract base type of a [GeneratedComClass] type would be reasonable to have in a parameter list and would be expensive to reliably detect), but we could design some simple rules to limit invalid usage.

Some of the integration tests are disabled due to the following issue:

Since CreateObjectFlags.Unwrap will unwrap any Managed Object Wrapper from any ComWrappers instance, we can easily get into a bad state if a COM object is implemented by ComWrappers under the hood. Our tests capture this pretty well as the "native" side is loaded into a separate ALC, so the tests fail as the underlying managed object cannot be cast to the interface on the "managed" side of the test. We need to determine a solution for this problem and enable those tests before we merge in this work.

Author:	jkoritzinsky
Assignees:	-
Labels:	area-System.Runtime.InteropServices
Milestone:	-