require-meta-schema should allow variable schema

[bmish]

If someone wants to use a variable or function call to get the value for any of the meta properties, that should be allowed.

{
  schema: baseRule.meta.schema
}

{
  schema: getSchema()
}

Example: https://github.com/typescript-eslint/typescript-eslint/blob/ad412cdd74dc5619fbe4bf27c0a5eb5c5a4b65ca/packages/eslint-plugin/src/rules/brace-style.ts#L27

This issue is not specific to TypeScript.