src/vs/workbench/services/search/common/searchService.ts/SearchService/getSchemesInQuery
class SearchService:	private getSchemesInQuery(query: ISearchQuery): Set<string> {
		const schemes = new Set<string>();
		query.folderQueries?.forEach(fq => schemes.add(fq.folder.scheme));

		query.extraFileResources?.forEach(extraFile => schemes.add(extraFile.scheme));

		return schemes;
	}