Additional Spreadsheet Factory Changes

I wanted to create a merge request before I lose track of changes I am continuing to make to the spreadsheet factories. So far, I have:

• Split up the original get_summary_flags function into two (get_summary_readings and match_summary_flags)
• Called get_summary_readings BEFORE iterating through measurement spreadsheets, this speeds up the script significantly
• Added try statement for scale_value because it can be located in different cells