This change ensures that when calling `requestContext.SendError` you are only able to supply parameters that match the language service beta protocol expected Error object. In other words, you have to provide an error message and optionally and error code.
# **BREAKING API CHANGES**
This will break displaying errors in Microsoft/vscode-mssql. I will be making changes to properly handle the error object shortly.
* Adding contract for returning Error objects as per LanguageService "protocol"
* Fixes throughout codebase to send only error message in error cases
Cleanup of CredentialServiceTest unit test class
Adding standard error handling for event flow validator
* Adding optional data field as per protocol spec
https://github.com/Microsoft/language-server-protocol/blob/master/protocol.md
* Adding optional validation for error objects
For whatever reason, Visual Studio throws a fit if a referenced project has a name
and the folder name (which is used to reference the project) is different than that name.
To solve this issue, I've renamed all the projects and folders to match their project
names as stated in the project.json.
