Frontend repo null/undefined mega clean up

[nguyenaiden]

Description: The front end repo currently is running into scalability issues.

1. The use of undefined and null as absence of value. This causes a ton of headache when trying to develop new features and make changes since we always have to guard against both, and sometimes TSlint does not recognize when a value is already guarded. This leads to a ton of unnecessary nullish coalescence and undefined checks.
2. Large components with a lot inline defined functions that makes unit testing very difficult. This results in putting a lot of trust and overhead on our e2e testing suite. While e2e testing is good, it should not be the only defacto line of defense against potential regressions. E.g: Swap.ts
3. Look to migrate data/state management to react query to promote composability, modularity, and testability of the methods.

Note: List is subjected to grow/change as we move forward with this plan.