feature: add "onError" hook to generated clients

[joshmossas]

Describe the feature

Adding an onError hook would allow you to intercept errors and trigger some side affect based on said error.

For example say your server begin returning a token expired error. Rather than needing to catch that error every time you call a procedure, an onError hook could trigger a side-effect that redirects the user to a login screen. Allowing you to handle this universal error in one place.

Additional context

None

Would you be willing to implement this feature?
Yes

[joshmossas]

Implementation Progress

Client	Implemented
Typescript	✅
Rust
Dart	✅
Swift	✅
Kotlin	✅

[joshmossas]

Finished in #102

Support not added for rust ATM since I don't feel like it right now