Enable hosts to compile strong-named assemblies on all platforms by supp...

[tmat]

...lying public key via compilation options and also enable OSS signing with such key

Fixes #567

[tmat]

/cc @gafter @AlekseyTs @VSadov @jaredpar @VladimirReshetnikov

[tmat]

/cc @jasonmalinowski @davidfowl

[tmat]

/cc @AnthonyDGreen @theoy -- this change updates public API surface.

[gafter]

Any particular reason you swapped this around? This is just going to confuse the translators.

[tmat]

@gafter Yes, to match C# order -- I need to create the diagnostic in shared code and C# had a different order.

[gafter]

Other than the strange indentation issue, looks good to me.

[tmat]

@gafter I fixed the indentation. Not sure why the VB formatter decided to insert it.

[jaredpar]

Should we abstract all of the Crypto fields into a separate type? It seems fragile to have properties where the doc (paraphrased) says:

if this is non-null then this other property must be null

Feel like this will be much easier to manage if it's a separate type which encapsulates the various states the data can be in.

[tmat]

@davidfowl Sounds like a bug in JSON serializer.

[tmat]

@jaredpar I don't think that's really necessary. It's trivial to validate the requirement and report diagnostics, which is what we are doing.

[tmat]

@davidfowl I guess that it can be serialized if the CryptoPublicKey is specified?