ARROW-3631: [C#] Add Appveyor configuration

[wesm]

No description provided.

[wesm]

cc @chutchinson for review

[eerhardt]

Looks good to me! Thanks for doing this, @wesm.

[chutchinson]

@wesm Looks good.

Question for @eerhardt - do you think it's important to specify TFM to dotnet test? There are some timezone-related tests in the most recent pull request that may fail because .NET Core does not currently embed time zone information in the runtime.

[wesm]

Successful appveyor build on my fork: https://ci.appveyor.com/project/wesm/arrow/builds/22287780

[eerhardt]

If you don’t specify a TFM, it runs against all the TFMs in the csproj. We only have 1, so I think we are fine here.

[eerhardt]

@wesm - I see this didn't fully fix the issue. The C# tests are not running in CI because the filtering logic needs to be updated.

For example see https://ci.appveyor.com/project/ApacheSoftwareFoundation/arrow/builds/22671460/job/nk1nn59k5njie720

Build started
git clone -q https://github.com/apache/arrow.git C:\projects\arrow
git fetch -q origin +refs/pull/3662/merge:
git checkout -qf FETCH_HEAD
Running Install scripts
python ci\detect-changes.py > generated_changes.bat
Affected files: [u'csharp/src/Apache.Arrow/Field.Builder.cs', u'csharp/src/Apache.Arrow/Schema.Builder.cs', u'csharp/test/Apache.Arrow.Tests/SchemaBuilderTests.cs', u'csharp/test/Apache.Arrow.Tests/TypeTests.cs']
Affected topics:
{'c_glib': False,
 'cpp': False,
 'dev': False,
 'docs': False,
 'go': False,
 'integration': False,
 'java': False,
 'js': False,
 'python': False,
 'r': False,
 'ruby': False,
 'rust': False,
 'site': False}
call generated_changes.bat
call ci\appveyor-filter-changes.bat
===
=== No C++ or Python changes, exiting job
===
Build was forcibly terminated
Build success

I can fix up the filtering logic. But my question is: what is the process here? Do I re-open the ARROW-3631 JIRA to do the work? Or do I log a new JIRA?