Consolidate and clean-up Fetch CSV file interactions

[oree-xx]

Fixes

• Fixes Consolidate and clean-up Fetch CSV file interactions #282

Description

• Cleaned up repeated write_to_sv functions in fetch scripts.
• Added rows_to_csv function to shared.py for appending data to csv file.
• Removed the initialise_data function in arxiv fetch script
• Changed the function name data_to_csv to dataframe_to_csv

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[TimidRobot]

Please update per #217:

        with open(FILE_COUNT, "r", encoding="utf-8") as file_obj: