fix(tokens): PostDeposit hook

[daniel-savu]

The PostDeposit hook was running inside try_mutate_account, so the user's balance was still equal to the pre-deposit amount. This caused certain post-deposit actions to fail.

Reason why this was not caught in the tests

The post-hook tests just increment a variable, so there are no real side effects. I thought about adding balance-changing posthooks inside the mock runtime, but those hooks would affect the results of many other tests. I don't think there's an easy way to use multiple mock runtimes in unit tests either.

[xlc]

one why to write tests for this is to instead of just record call count, record the hook parameters in a vector. then you can assert the vector for expected number of calls & expected called values

[daniel-savu]

one why to write tests for this is to instead of just record call count, record the hook parameters in a vector. then you can assert the vector for expected number of calls & expected called values

I tried implementing your suggestion but realised that call parameters were correct, it was the timing of the call that was wrong.

As such, I added checks in the mock posthooks which enforce that the balance of the account is at least amount. I was then able to test the edge case that this PR fixes.

[xlc]

In that case you can read the account data and have it saved to the vector for assertion as well. But I am ok with your current approach.

[xlc]

should use assert in the hooks instead of ensure