## What changes were proposed in this pull request?
This adds a new API `TaskContext.getLocalProperty(key)` to the Python TaskContext. It mirrors the Java TaskContext API of returning a string value if the key exists, or None if the key does not exist.
## How was this patch tested?
New test added.
Author: Tathagata Das <tathagata.das1565@gmail.com>
Closes#21437 from tdas/SPARK-24397.
## What changes were proposed in this pull request?
Adds basic TaskContext information to PySpark.
## How was this patch tested?
New unit tests to `tests.py` & existing unit tests.
Author: Holden Karau <holden@us.ibm.com>
Closes#16211 from holdenk/SPARK-18576-pyspark-taskcontext.
