Test adjustments and improvements.

* Reducing code duplication
* Using import destructuring.
* Ignoring integration test file output.
* Changing package 'test' script to not use hashbang execution.
* Explicitly requiring jake rather than relying on global import
* Fixing integration tests to run on Windows.
* Fixing no-sparse-arrays eslint error.
* Fixing assertion param ordering
* Making test tmp dir deletion/creation easier.
* Fixing windows jake batch script.
* Ensuring `jake lint` passes.

Author: Tzrlk

jake.bat

@@ -1,2 +1,2 @@
 @ECHO OFF
-@"%~dp0node.exe" "%~dp0/node_modules/jake/bin/cli.js" %*
+node "%~dp0bin/cli.js" %*