tedious arrayToGuid implementation

[Jeremy Danyow]

hi all- I'd like to submit a PR with perf improvement for the arrayToGuid implementation but was hoping to get some feedback on my question here first: https://github.com/tediousjs/tedious/issues/429

I'm not super familiar with the library or it's history so I didn't want to dive in and send a PR that had no chance of acceptance without getting some feedback from the maintainers.

let me know what you think!