Port System.Runtime.InteropServices docs for .NET 9 APIs

[carlossanlop]

Below is the list of APIs that still show up as undocumented in dotnet-api-docs and were introduced in .NET 9.

Full porting instructions can be found in the main issue.

This task needs to be finished the day before the RC2 snap (September 15th).

Scroll right to see the details:

API	Summary	Parameters	TypeParameters	ReturnValue
M:System.Runtime.InteropServices.CollectionsMarshal.GetValueRefOrAddDefault3(System.Collections.Generic.Dictionary2.AlternateLookup{0,1,2},2,System.Boolean@)	Missing	Missing	Missing	Missing
M:System.Runtime.InteropServices.CollectionsMarshal.GetValueRefOrNullRef3(System.Collections.Generic.Dictionary2.AlternateLookup{0,1,2},2)	Missing	Missing	Missing	Missing
M:System.Runtime.InteropServices.Marshalling.ComVariantMarshaller.ConvertToManaged(System.Runtime.InteropServices.Marshalling.ComVariant)	Missing	Missing	NA	Missing
M:System.Runtime.InteropServices.Marshalling.ComVariantMarshaller.ConvertToUnmanaged(System.Object)	Missing	Missing	NA	Missing
M:System.Runtime.InteropServices.Marshalling.ComVariantMarshaller.Free(System.Runtime.InteropServices.Marshalling.ComVariant)	Missing	Missing	NA	NA
M:System.Runtime.InteropServices.Marshalling.ReadOnlySpanMarshaller2.ManagedToUnmanagedOut.GetManagedValuesDestination(System.Int32)	Present	Missing	NA	Present
M:System.Runtime.InteropServices.Marshalling.ReadOnlySpanMarshaller2.ManagedToUnmanagedOut.GetUnmanagedValuesSource(System.Int32)	Present	Missing	NA	Present
M:System.Runtime.InteropServices.Marshalling.ReadOnlySpanMarshaller2.ManagedToUnmanagedOut.ToManaged	Present	NA	NA	Missing
N:System.Runtime.InteropServices.Swift	Missing	NA	NA	NA
T:System.Runtime.InteropServices.Swift.SwiftSelf1	Present	NA	Missing	NA

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