Make "and/or" so that if you're bringing in candidates regularly, that's enough for a 3

Minor amendments

Fix and simplify flow type-checking

This allows importing from and saving to Google Sheets. This is totally
optional and the URLs will still work as they always have.
The flow is something like this:

* Use the Authorize button to authorize the app to access your Google Sheets with
  OAuth.
* Then you have an input that accepts a sheet ID and three buttons:
import, create/save, and sign out
* The sheet ID field accepts a sheet ID. You can simply paste in a URL
  from an open Google doc and the page extracts the sheet ID
  automatically.
* Import imports a Google Sheet into the Snowflake page, using the
  entered sheet ID.
* The create button is shown when no sheet ID has been entered. This
  creates a new sheet, adds the sheet ID to the input, and shows a link
  that takes you to the sheet.
* If you've entered a sheet ID, the create button becomes a save button
  and you may click it to update the sheet corresponding to the ID.
* Finally, the sign out button revokes access to Google Sheets and takes
  you back to the original view, with only an Authorize button.

There's not a ton of error-checking. If you try to import a sheet that
doesn't have data in the expected format, it's not going to go well.
Don't do that.

The sheet doesn't yet store name or title, but that's coming up in
another PR.

Add option to import from/save to Google Sheets

Add a text field for track notes

Add a longer description for each track

We don't do Android.

Mobile improvements

Mentorship

Web client track

Org design track

Evangelism track update

Services & APIs track review