[Cashtab] notification duration set as app parameter

Summary: Added notification duration as parameter in Ticker.js. Related to task T1921

Test Plan:
cd web/cashtab
npm start
send XEC, ensure notification duration is correct,
create token, ensure notification duration is correct,
send token, ensure notification duration is correct,
receive XEC, ensure notification duration is correct,
receive token, ensure notification duration is correct,

Reviewers: bytesofman, #bitcoin_abc

Reviewed By: bytesofman, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D10398