[SPARK-31763][PYSPARK] Add inputFiles method in PySpark DataFrame Class.

[iRakson]

What changes were proposed in this pull request?

Adds inputFiles() method to PySpark DataFrame. Using this, PySpark users can list all files constituting a DataFrame.

Before changes:

>>> spark.read.load("examples/src/main/resources/people.json", format="json").inputFiles()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/***/***/spark/python/pyspark/sql/dataframe.py", line 1388, in __getattr__
    "'%s' object has no attribute '%s'" % (self.__class__.__name__, name))
AttributeError: 'DataFrame' object has no attribute 'inputFiles'

After changes:

>>> spark.read.load("examples/src/main/resources/people.json", format="json").inputFiles()
[u'file:///***/***/spark/examples/src/main/resources/people.json']

Why are the changes needed?

This method is already supported for spark with scala and java.

Does this PR introduce any user-facing change?

Yes, Now users can list all files of a DataFrame using inputFiles()

How was this patch tested?

UT added.

[iRakson]

cc @HyukjinKwon Kindly review this PR

[HyukjinKwon]

Let's to a try-finally, and use this_naming_rule per PEP8.

tpath = tempfile.mkdtemp()
shutil.rmtree(tpath)
try:
    ...
finally:
    shutil.rmtree(tpath)

[HyukjinKwon]

You can just return list(self._jdf.inputFiles())

[HyukjinKwon]

ok to test

[SparkQA]

Test build #123181 has finished for PR 28652 at commit 6df9b76.

• This patch fails PySpark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[iRakson]

retest this please

[SparkQA]

Test build #123183 has finished for PR 28652 at commit 729ff00.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[HyukjinKwon]

Merged to master.

[iRakson]

Thank You. @HyukjinKwon
Is it a good idea to add this method in 3.0 as well, as this do not add any major change. ?
Also inputFiles() is being used since 2.0 in scala.

[HyukjinKwon]

Technically this is a new API and we shouldn't backport it.