Move blockchain-interacting logic from Raiden class to state machine

[andrevmatos]

Description

Currently, there're some methods on the Raiden class (public interface of SDK) which, although not changing directly the state, interact with blockchain in a read-write manner and should be put in the state machine as their own epics instead, and through their own AsyncActionCreators

Acceptance criteria

• No rw blockchain logic is present on Raiden

Tasks

• [ ] mint becomes an AAC and epic (suggestion: on channels/)
• [x] depositToUDC becomes an AAC and epic (suggestion: on services/)
• [ ] transferOnchainBalance becomes an AAC and epic (suggestion: on channels/)
• [ ] transferOnchainTokens becomes an AAC and epic (suggestion: on channels/)

Why do this?

Improves code quality, logging and testability of the functions. Long wanted tech debt that makes for better readability and maintainability of the code.