DataSpreadsheet refactor

[elycheea]

Followup from DataSpreadsheet release review that we never got around to closing out.

We can recheck current code coverage, but believe @matthewgallo and @davidmenendez both contributed to get this to about 80-90%

• a lot of missing code coverage
• handleKeyPress has a lot of redundant code
• not a deal breaker, but considering how large the file is a lot of the handler initializers may want to be moved into separate util or hook files at some point
• if you command click the same 2 cells over and over again they just keep getting added to the selection
• isHoldingCommandKey is defined a few different times, so it should probably be a utility

Originally posted by @davidmenendez in #2324 (comment)

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1. DataSpreadsheet refactor: Reduce redundancy in handleKeyPress #4187
   component: DataSpreadsheet version: 2 +2
2. DataSpreadsheet refactor: Reduce duplication with isHoldingCommandKey #4188
   component: DataSpreadsheet version: 2 +2
3. DataSpreadsheet refactor: Prevent Cmd (Ctrl) + click from re-adding the same cells to a selection #4241
   component: DataSpreadsheet version: 2 +2
4. DataSpreadsheet refactor: Refactor handlers into separate utilities or hooks #4597
   component: DataSpreadsheet status: needs triage 🕵️‍♀️ version: 2 +3