fix: the address screen shows a token just added at its fetched balance, not 0.0000 (closes #516)

A balance refresh that returns now draws the balances on AddressDetail or
AddressToken again when that screen is up, not only the wallet list; their
transaction lists are left alone. Every add path on AddToken and
SettingsAddToken tracks a token through one step, trackToken(), which also
marks it not yet fetched: its line reads `quantity unknown` instead of 0.0000
until a refresh that started with it tracked has fetched every address's
token balances. To tell an address whose token balances the explorer did not
return, the refresh takes them off its copy of the wallets before fetching.

Model: opus-5-5

tests/flashLine.test.js

@@ -88,6 +88,7 @@ describe.each([
             showFlash: (msg) => flashes.push(msg),
             escapeHtml: (s) => s,
             goBack: () => {},
+            trackToken: () => {},
         }));
 
         require("../src/popup/views/" + view).init({