[SPARK-17200][PROJECT INFRA][BUILD][SPARKR] Automate building and testing on Windows (currently SparkR only)

## What changes were proposed in this pull request?

This PR adds the build automation on Windows with [AppVeyor](https://www.appveyor.com/) CI tool.

Currently, this only runs the tests for SparkR as we have been having some issues with testing Windows-specific PRs (e.g. https://github.com/apache/spark/pull/14743 and https://github.com/apache/spark/pull/13165) and hard time to verify this.

One concern is, this build is dependent on [steveloughran/winutils](https://github.com/steveloughran/winutils) for pre-built Hadoop bin package (who is a Hadoop PMC member).

## How was this patch tested?

Manually, https://ci.appveyor.com/project/HyukjinKwon/spark/build/88-SPARK-17200-build-profile
This takes roughly 40 mins.

Some tests are already being failed and this was found in https://github.com/apache/spark/pull/14743#issuecomment-241405287.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #14859 from HyukjinKwon/SPARK-17200-build.