* fix(swap): use undefined as initial currencyId state

Null should be used for a selection state, not an unknown state. undefined may signify that a currency was passed in the URL but not yet parsed.

* perf(swap): initialize swap with url

Initializes SwapState with URL parameters so that currency input may be rendered on the first frame.

* test(swap): update hooks tests

* test: fix casing

* fix: check nullish to allow eg 0