[Cashtab] Tx History should immediately update to include newly added contacts

Summary: Related to T2724. Changed logic in updateContactListInLocalForage to setContactList(contactListArray), leveraging Context to make the new contactList immediately available to the Tx component. Renamed updateContactListInLocalForage to updateContactList.

Test Plan:
cd web/cashtab && npm start
from TxHistory, expand a Tx from a non-contact
click the Add To Contacts button
navigate back to TxHistory
observe that 'from newContact' appears on Txs from the new contact

navigate to the configure screen
delete the new contact
navigate back to TxHistory
observe that 'from newContact' no longer appears on Txs from the (former) new contact

grep -r 'updateContactListInLocalForage' src/ should return no results.

Reviewers: bytesofman, #bitcoin_abc

Reviewed By: bytesofman, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D12179