Feature/transaction support

[YutaUra]

I wrote an implementation to support transaction rollback using SAVEPOINT

Let me first say that the implementation is not yet perfect.
I believe the implementation is complete. I've added a test case, so I'm thinking it's probably okay.

I have confirmed that the test case I added succeeds when using sqlite.
I have tried testing with Postgres instead of SQLite and have confirmed that it succeeds.
↓ This is its code.
YutaUra#1

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If you don't mind, I'd like to get your feedback on the changes at this time.

[YutaUra]

@Quramy I think I've got it all implemented. I would love to have your review! ❤️

[Quramy]

Hi. Thanks for your PR.

I think this feature should remain disabled by default .

1. Currently Prisma's $transaction does not support nested transaction, Support "nested" transactions in interactive transactions prisma/prisma#15212. How Prisma itself supports nested transactions will change the positioning of this feature. In this sense, I think this feature is experimental.
2. $executeRawUnsafe("SAVEPOINT ...") might not work at NOSQL datasource environment.

Would you reverse the disableReproduceTransactionRollback flag ? (i.e. enableExperimentalRollbackInTransaction )

[YutaUra]

@Quramy Thanks so much for the review, I really appreciate it. I agree with your feedback!

I pushed the fixed code. Please feel free to tell me if you find anything that needs to be fixed!

[Quramy]

@YutaUra Thanks, great work 🎉