function rangeExtends(extendingRange, rangeToExtend) {
    return rangeToExtend.getStartPosition().equals(extendingRange.getStartPosition())
        && rangeToExtend.getEndPosition().isBeforeOrEqual(extendingRange.getEndPosition());
}
@param previewSuffixLength Sets where to split `inlineCompletion.text`.
	If the text is `hello` and the suffix length is 2, the non-preview part is `hel` and the preview-part is `lo`.