[SWF Editor] Change Language Service (LS) to yield validation messages for SWF file

LS validations are going to be a combination of JSON Schema validations and Custom validations.

VS Code:

• JSON language -> LS needs to provide only the Custom validations
• Serverless Workflow (JSON) language -> LS needs to provide both JSON Schema and Custom validations

Webapp:

• SWF Text Editor -> We can register the JSON Schema and ask the LS only for the Custom validations or, we can not register JSON Schema and let the LS do everything
• SWF Diagram Editor -> The LS will provide everything about validation