[Bug 56136] ImageGetDigestStream does not behave the same as on windows

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=56136

--- Comment #7 from Zeb Figura  ---
Creating a test DLL isn't hard. We don't even need to do it manually like in
kernel32:loader. Tests are compiled with mingw, and we have build system
support for adding a custom DLL as a resource (cf. msi, setupapi for examples).

I'm just confused about why we need a dedicated test DLL. As far as I can tell
the function just extracts imports and resources [which we could test against
any system module, or the test exe itself] and debug info [which I don't think
we can meaningfully test and probably don't even need to implement].