Python APIs in backend

[dotbugfix]

init_excel_file(file_stream)
get_excel_headers(): list of strings
init_pdf_dir(path, file_name_mapping) (file_name_mapping is str "{col1}_{col2}")
set_email_metadata(to_col, cc_column, subject_template, body_template)
set_email_server(from_email, reply_to_email, server_addr, server_port, username, password)

get_report_summary(): [{donor, beneficiary, to, cc, report_pdf_name, email_subject, email_body)]
send_test_email({same_dict}, test_email_address)
send_emails({same_dict})

[ajaynair]

[ajaynair]

We can change init_pdf_dir to init_attachment_dir
We can remove donor and beneficiary from here: get_report_summary(): [{donor, beneficiary, to, cc, report_pdf_name, email_subject, email_body)]