Let the user skip backup message generation and record it in alert store

Summary: This differential enables user to skip siwe backup message generation. Additionally alert store is used to prevent the screen from appearing too frequently.

Test Plan:

1. Build the app
2. Log in as SIWE user
3. Ensure that there is a Skip button on a backup message screen.
4. Click skip button. Ensure that screen disappears.
5. Play with the app. Kill and re-open it multiple times. Ensure that screen doesn't appear again.

Reviewers: ginsu, ashoat

Reviewed By: ginsu, ashoat

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D11782