Simplify and refactor Send screen

[vkjr]

Problem

The logic of Send screen is extremely complicated to understand and to change. It mixes all kinds of logic and contains many calculations. Only the top-leve 'let' contains 160 lines. In order to work effectively with this critical part of code it need to be refactored and simplified

Implementation

Suggested implementation is to move all the calculations inside view to subscriptions. That subscriptions can be used in sub-views. Brunch with suggested implementation

Acceptance Criteria

Send logic is easy to understand. No regressions.

Notes

Future Steps

[churik]

Postponed to 2.33 due to limited capacity

cc @shivekkhurana