SwaggerEditor@next - expose VSCode providers to the plugin system

[char0n]

Currently there is only one way how to inject custom providers into Monaco Editor. This requires to manually dispose for all registered providers (assuming that their disposables are available) and register the custom ones. This is complex process and error-prone process.

The scope of this issue is to remedy the situation by exposing the providers to plugin system and letting plugin system consumer to override them at his/hers will.