Allow upload gzipped files via apache_beam.io.gcp.gcsio.GcsIO with proper content-encoding

To reduce the size of uploaded files we decided to gzip it before upload. Unfortunately, we noticed that we don't have content-encoding 'gzip' in the uploaded files metadata. I rechecked the code and noticed that there is no way to pass gzip encoding on
```

apache_beam.io.gcp.gcsio.GcsIO.open()
```

Also, I noticed that apache_beam.io.gcp.gcsio.GcsUploader doesn't support uploading for gzipped files.

To resolve this problem we need to allow pass gzip_encoded option, which can be passed to apitools.base.py.transfer on
```

GcsUploader.__init__()

```

Is there any possibility that you apply the required changes soon?

*What steps to reproduce the problem?*
1. Prepare gzip encoded file for example pdf
2. Upload it to GCS using
```

from apache_beam.io.gcp.gcsio import GcsIO

def upload_gzipped_pdf(gzipped_pdf, path)
with GcsIO().open(path,
'w') as f:
f.write(gzipped_pdf)

```

3. Try to download uploaded file via browser

*What is the expected result?*
I see the file content properly

*What happens instead?*
I have a broken document

*Possible resolution after implementing expected changes*
```

from apache_beam.io.gcp.gcsio import GcsIO

def upload_gzipped_pdf(gzipped_pdf, path)
with GcsIO().open(path,
'w', gzip_encoded=True) as f:
f.write(gzipped_pdf)

```

Imported from Jira [BEAM-7411](https://issues.apache.org/jira/browse/BEAM-7411). Original Jira may contain additional context.
Reported by: p35.