[mod] creating tui.py

* create tui.py with license statement
* move display_amount() and display_pubkey() to tui.py to prevent circular dependencies
* change display_amount() to prevent circular dependency with money.py.
    * Now display_amount() needs the ud_value parameter.
    * display_amount() is no more async
* mod tx.py and test_unit_tx.py to match new location of the two features.