isExportProvided(module, exportName) {
		const mgm = this._getModuleGraphModule(module);
		const result = mgm.exports.isExportProvided(exportName);
		return result === undefined ? null : result;
	}
@param {Module} module the module
@param {string | string[]} exportName a name of an export
@returns {boolean | null} true, if the export is provided by the module.
null, if it's unknown.
false, if it's not provided.