add integration tests for meta transactions

[jakmeier]

Goal: Assure full test coverage of meta transactions.

We already have unit test that trigger all of the potential errors, except for the error about nested delegate actions.

Additionally, I propose to add tests on the trait User abstraction level, basically end-to-end as far as nearcore is concerned. There, I would like to see one test for each type of action. And a couple of common scenarios.

• Remove nested delegate actions error (feat: type guarantees for NonDelegateAction #8538)
• Extend trait User to execute meta transactions (test: first rust meta tx integration tests #8551)
• Add test for CreateAccount (test: meta transaction account creation scenarios #8568)
• Add test for DeployContract (test: every action in a meta transaction #8559)
• Add test for FunctionCall (test: first rust meta tx integration tests #8551)
• Add test for Transfer (test: first rust meta tx integration tests #8551)
• Add test for Stake (test: every action in a meta transaction #8559)
• Add test for AddKey (test: every action in a meta transaction #8559)
• Add test for DeleteKey (test: every action in a meta transaction #8559)
• Add test for DeleteAccount (test: every action in a meta transaction #8559)
• Test scenario for fungible token transfer (test: meta transaction FT transfer #8564)
• Test for onboarding a user with an implicit account but no tokens (test: meta transaction account creation scenarios #8568)
• Test when executing a meta transaction with a function call access key and allowance (instead of full access key) (test: access keys scenarios in meta transactions #8570)

[jakmeier]

I think now that #8538 has removed the nested delegate error, we don't really need a test for it.

We could only add a test for deserialization to fail. That seems to be an overkill for integration tests. We already have unit tests in core/primitives/src/delegate_action.rs that check (de-)serialization works as intended.

=> I will mark that point as done.

[jakmeier]

All tests required should be coded now, just need to pass code reviews and merge them.
Good news: Everything looks like it functions as intended, I didn't find any bugs with my tests. (Only one or two misunderstanding of my own how things works.)

[jakmeier]

All merged! 🎉