refactor(utils): add tmpdir function

lib/utils/Utils.js

@@ -131,6 +131,33 @@ function deepCompare(obj1, obj2) {
   });
 }
 
+/**
+ * Returns the os tmpdir.
+ * @returns {string}
+ */
+function getTmpdir() {
+  const env = BROWSER ? {} : process.env;
+
+  const is_windows = process.platform === 'win32';
+  const trailing_slash_re = is_windows ? /[^:]\\$/ : /.\/$/;
+  
+  let path;
+
+	if (is_windows) {
+	  path = env.TEMP || env.TMP ||
+	    (env.SystemRoot || env.windir) + '\\temp';
+	} else {
+	  path = env.TMPDIR || env.TMP ||
+  		env.TEMP || '/tmp';
+	}
+
+	if (trailing_slash_re.test(path)) {
+	  path = path.slice(0, -1);
+	}
+
+	return path;
+}
+
 /**
  * Finds a string between two delimiters.
  *
@@ -284,7 +311,7 @@ function refineNTokenData(data) {
 const errors = { InnertubeError, UnavailableContentError, ParsingError, DownloadError, MissingParamError, NoStreamingDataError, OAuthError };
 
 const functions = {
-  findNode, observe, getRandomUserAgent, generateSidAuth, generateRandomString, getStringBetweenStrings,
+  findNode, observe, getTmpdir, getRandomUserAgent, generateSidAuth, generateRandomString, getStringBetweenStrings,
   camelToSnake, isValidClient, throwIfMissing, timeToSeconds, refineNTokenData
 };