Pure unit tests and separate implementation tests from standard compliance tests

[MMujtabaRoohani]

I have redesigned the sandbox tests to fix a number of issues that I noticed.

1. The tests lack isolation; for instance, modifying a jetton wallet contract will cause the jetton minter contract tests to fail unexpectedly.
2. Setting a smart contract’s state by sending messages to it, increases dependency on other functionalities, reducing test isolation.
3. Tests are dependent on each other, for instance, running a test in isolation by using it.only fails because the deploy tests is skipped that deploys the contract.
4. Tests are fragile towards minor changes in configuration that requires regular updation to ensure tests are green. Failure to update it results in failing tests, making it difficult for devs to build their solution on the standard code base.
5. Bulk operations take long time, requiring them to be commented out.

My approach ensures tests are isolated, independent, and focused on verifying single transactions on our system under test (sut) instead of the whole chain of transactions.

I would love if contributors can review the changes and share their valuable feedback with me.

[MMujtabaRoohani]

Thanks for the approval @Charria12. When do you think this can be merged?