Transactions - change show all key from "~" to "@"

Summary: (some) international keyboard layouts can not type "~" in a way as to trigger this so use "@" instead. Save the suggested "+" as that seems like it would be useful for some future "adding stuff" keyboard workflow. Pretty stoked to get this squared away as I am quite confident our unreleased product will now be a huge smashing success. Ref T6683.

Test Plan: made sure my choice was okay via https://en.wikipedia.org/wiki/Dead_key#Dead_keys_on_various_keyboard_layouts; used the "@" key to show all transactions

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T6683

Differential Revision: https://secure.phabricator.com/D10983