Port FxCop rule RS0015: #N/A

[ghost]

Title: Always consume the value returned by methods marked with PreserveSigAttribute

Description:

PreserveSigAttribute indicates that a method will return an HRESULT, rather than throwing an exception. Therefore, it is important to consume the HRESULT returned by the method, so that errors can be detected. Generally, this is done by calling Marshal.ThrowExceptionForHR.

Dependency: None

Notes:

[srivatsn]

This rule in in the unfactored location. It needs to be moved to the InteropServices.Analyzers location. As part of this, implement some unit tests for this rule (#343)

[mavasani]

Not sure if this needs to stay in 15.3 or can be moved out. Marking as 15.3 for now - @jinujoseph

[Evangelink]

@mavasani Is it still worth to implement this rule as such? It feels like there is an important overlap with CA1806 (there is a special case for HRESULT).