[Cashtab] Rename contacts
[Cashtab] Rename contacts

Summary: Supersedes D11323.  Rename contact function.

Test Plan:
- navigate to the Settings screen, open the contact list dropdown and verify the rename icon is not rendered for empty contact lists
- send a tx to this wallet and then in the tx history click on the Add to contact link and ensure routing to the contact list dropdown
- rename the contact and ensure the change in name persists even if the browser is restarted
- rename the same contact multiple times and ensure the latest change is persisted

Reviewers: #bitcoin_abc, kieran709

Reviewed By: #bitcoin_abc, kieran709

Differential Revision: https://reviews.bitcoinabc.org/D11344

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