[SWF Editor] Create a Language Service for Serverless Workflow

Using only Monaco's language service capabilities, we don't have the option to include multiple files into the validation/autocompletion features, for example.

Implementing a Language Service for Serverless Workflow will allow us to work with a "workspace" instead of single files. By making this Language Service decoupled from the Editor itself, we can reuse it in multiple places, being it on the VS Code extension or a Web-based Editor, like in KIE Sandbox, for example.