[PRA-92] Add a context manager to create pre-configured Spark session

[theoctober19th]

This PR introduces a context manager SparkSession in spark8t.session which enables the users to create a pre-configured Spark session that comes with the following preconfigured:

1. The K8s master
2. The Spark Service account props
3. The driver ip address
4. Exemption of K8s master in the proxy settings (just in case it is being run on environments like PS7)

The objective here is to make it easy for users to use Spark inside the Spark pipeline. An example on how this can be used can be seen here.

Test mechanism:

1. Unit tests are in place to ensure that the spark session calculates correct ip address for host, k8s master, does close spark session at the end of the session, and also adds k8s master to no_proxy environment variable.
2. Integration tests are in place to ensure that this context manager can be used to run Spark jobs.
3. Also tested in the Kubeflow <> Spark context here

[Batalex]

I'm so happy that this feature is finally here!
For the longest time I would see this PR and think "oh this is neat, wonder when we will work on it again"
I left a few minor comments, but otherwise great job!

[Batalex]

LGTM, we can leave the IPV6 question for later when we actually face the issue

[welpaolo]

LGTM. Great work Bikalpa