[discussion] Consider reducing amount of global options

Description

A question was raised out of #2429. We have quite a few "global" options (those available across all generators), which either aren't relevant to or aren't supported by many generators.

Should we consider thinning out these global options, or more clearly identifier which options are supported by which generators?

Per #2429, we should also identify if there may be other options which exist in global options with sibling options only available in additionalProperties.

openapi-generator version

Pre-4.0

cc @OpenAPITools/generator-core-team