Deconfliction with YAML extension's language service

[bwateratmsft]

RedHat's YAML extension provides an exceptional language service for YAML files including compose. The compose schema needs some attention, but that is orthogonal to RedHat's work.

Clients of this language service (especially the Docker extension) should be able to specify whether certain features are desired from the client's perspective, and if not, they can be disabled.

This would also resolve redhat-developer/yaml-language-server#715.