[REVIEW] Update orc reader and writer fuzz tests

[galipremsagar]

This PR introduces:

• Fixes to some of the breakages introduced by the latest pyorc in using pyorc.Struct.
• Adapt to list dtype parameter changes introduced previously.
• Misc fixes required for proper fuzz test runs.

[vuule]

LGTM, but it's kind of hard to understand why some changes were made (without the detailed description).

[vuule]

I wondered what the desired behavior is here, i.e. whether ORC as a format supports having no columns.
I think we also have some issues writing empty dataframes to ORC.

[galipremsagar]

I guess we need to write an empty struct. With pyorc we can do it this way:

>>> import pyorc
>>> import pandas as pd
>>> output = open("sample.orc", "wb")
>>> writer = pyorc.Writer(output, pyorc.Struct())
>>> writer.close()
>>> pd.read_orc('sample.orc')
Empty DataFrame
Columns: []
Index: []

Looks like I also need to make some code-changes in this PR. I'll update this PR.

[galipremsagar]

LGTM, but it's kind of hard to understand why some changes were made (without the detailed description).

Updated the code-changes with comments, this is ready for a re-review.

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[vuule]

found a typo, LGTM otherwise

[galipremsagar]

@gpucibot merge