Use gspread to create a spreadsheet from the output of
compare_cts_reports.py.
Bug: 306351009
Test: python3 generate_spread_sheet.py \
--compared_result compare_result/diff.csv \
--sheet_name "CTS Comparasion Report" \
--credentials_dir ~/.config/gspread/
Change-Id: I5199d4d0690e9b29e8b5cef5798b16481d589f42