Improve OnUnhandledException errors when loading Plugins

[vncoelho]

Currently it is hard to know which plugin is causing the exception

neo> Unhandled exception. System.TypeInitializationException: The type initializer for 'Neo.NeoSystem' threw an exception.
 ---> System.TypeLoadException: Could not load type 'Grpc.Core.ConnectivityState' from assembly 'Grpc.Net.Common, Version=2.0.0.0, Culture=neutral, PublicKeyToken=d754f35622e28bad'.
   at System.Reflection.RuntimeAssembly.GetExportedTypes()
   at Neo.Plugins.Plugin.LoadPlugin(Assembly assembly) in /opt/neo/src/Neo/Plugins/Plugin.cs:line 171
   at Neo.Plugins.Plugin.LoadPlugins() in /opt/neo/src/Neo/Plugins/Plugin.cs:line 206
   at Neo.NeoSystem..cctor() in /opt/neo/src/Neo/NeoSystem.cs:line 112
   --- End of inner exception stack trace ---
   at Neo.NeoSystem.CurrentDomain_UnhandledException(Object sender, UnhandledExceptionEventArgs e) in /opt/neo/src/Neo/NeoSystem.cs:line 185
   at System.AppContext.OnUnhandledException(Object e)
/opt/start_node.sh: line 2:   116 Aborted                 (core dumped) ( cd /opt/node/Neo.CLI/; dotnet neo-cli.dll )

[vncoelho]

I opened two issues regarding this message.

In this one I would like to discuss the errors itself, a better tracing for all plugins loading.

That could possible directly provide a direction to which PLUGIN LOADING caused the problem.

[ajara87]

@vncoelho could you tell me what steps you followed to reproduce the error?

[vncoelho]

You can compile the neo-cli with all plugins

# https://github.com/neo-project/neo-node/commits/master-n3
NEO_CLI_BLOCKCHAIN_URL=https://github.com/neo-project/neo-node.git
NEO_CLI_BRANCH=master-n3
NEO_CLI_COMMIT=419c3f1d8ab8ab18bd702518b5590e6f9acfd2c4

# https://github.com/neo-project/neo/commits/master-n3
NEO_BLOCKCHAIN_URL=https://github.com/neo-project/neo.git
NEO_BLOCKCHAIN_BRANCH=master-n3
NEO_BLOCKCHAIN_COMMIT=004c97efd6629bef2feb48d72678d73cde114644

Then, you can startup a Seed Node with the following plugins: OracleService, RpcServer,RestServer,TokensTracker,StorageDumper, DBFTPlugin (watchonly), StateService and SignClient.

I am sending the .zip neo-cli on discord.

For some reasons, in some cases the SignClient Grpc libraries are conflicting with OracleService libraries.
I am understand, both of them require Grpc.
So, we need to include the *dlls in, at least, one the folder.

Perhaps because Signclient has a fixed Grpc version we are having this problem, which I am more focusing on discussing here #942

But the issue here I am discussing is more focused on the error message itself, that is should trace which *dlls it loaded. We could have some Debug mode for printing that on neo-cli.

[vncoelho]

#963

better logs still needed

[vncoelho]

Still need better logs, the first version of @ajara87 PR was better