Sheets: Make "batchGet"/range option of type string[] instead of string

[arthurjdam]

Not sure why the documentation doesn't agree, but there does not seem to be any way of sending a singular string as batchGet's "ranges" option
Example:
ranges: "TABONE!A1:B,TABTWO!A2:B" will fail
ranges: ["TABONE!A1:B", "TABTWO!A2:B"] works just fine

• npm test succeeds
• Pull request has been squashed into 1 commit
• I did NOT manually make changes to anything in apis/
• Code coverage does not decrease (if any source code was changed)
• Appropriate JSDoc comments were updated in source code (if applicable)
• Appropriate changes to readme/docs are included in PR

[JustinBeckwith]

Thank you so much for the PR! Sadly, this is an auto-generated file. Any fixes required will need to be made on the generator. We're tracking this over in #1266 :)