Allow disabling completions/tooltips in settings

[rchl]

The new version of https://packagecontrol.io/packages/LSP-json (not released at the time of writing) will provide schema validation and autocomplete for settings through json schemas. With that enabled, autocomplete values for settings end up being duplicated. It would be nice to have an option to disable PackageDev ability to provide completions.

[rchl]

Also same for tooltip with option descriptions as LSP-json also provides those.
Currently PackageDev seems to be the one winning the tooltip battle.