Sheets Exporter: Support new Spreadsheet, new sheet, exists data

[baruchiro]

After merging #118, need to validate the exporting to Google Spreadsheets code, includes

• Create a new Spreadsheet by name.
• Create a new sheet by const name.
• Read existed data from the sheet and merge with the new data.

[baruchiro]

On second thought, creating a new Spreadsheet by name should be implemented in the UI context, since we have two different areas in the app- the config editor (the UI) and the scraping that gets the config and doing the job.

If we are putting a new spreadsheet name in the config, then passing the config as an argument to the scraping, the scraping will create a new spreadsheet, but the config still defines the Spreadsheet name.

I mean, during the scraping, the SpreadsheetId value will change from the new Spreadsheet name to its SpreadsheetId, but we are not changing the config during the scraping, so the next time the config will still be with the Spreadsheet name instead of with an already exist SpreadsheetId.

@brafdlog WDYT?