Make library AOT compatible

[giggio]

Right now we are getting warnings, like:

/home/user/.nuget/packages/cloudnative.cloudevents.systemtextjson/2.7.1/lib/netstandard2.1/CloudNative.CloudEvents.SystemTextJson.dll : warning IL2104: Assembly 'CloudNative.CloudEvents.SystemTextJson' produced trim warnings. For more information see https://aka.ms/dotnet-illink/libraries [/app/consumer.csproj]
/home/user/.nuget/packages/cloudnative.cloudevents.systemtextjson/2.7.1/lib/netstandard2.1/CloudNative.CloudEvents.SystemTextJson.dll : warning IL3053: Assembly 'CloudNative.CloudEvents.SystemTextJson' produced AOT analysis warnings. [/app/consumer.csproj]

[jskeet]

I'm afraid I don't have enough experience with AOT (or time to get up to speed) to work on this. I'd happily review a PR to address it, however.

[giggio]

@jskeet I just added a PR for it, it was a lot of work, I need revision to make sure everything is ok.

[guillaume-chervet]

hi @jskeet , does this library is AOT compatible now?

I would like to use it for a test as an extention for https://github.com/AxaFrance/SlimFaas

[jskeet]

@guillaume-chervet: No, it isn't. There's an incomplete attempt in https://github.com/jskeet/sdk-csharp/tree/aot - it's possible that we could do this incrementally, but for the moment I'm afraid I don't have time to put into it. @captainsafia has expressed interest though, and can probably do a better job on this than I can anyway.

[guillaume-chervet]

Thank you @jskeet for your "very" quick answer.