[Backup/Flow] add new screens

The Backup Wallet flow is:
- precondition: flow triggered from Dashboard bottom notification
- **screen1 - Security** - displays info texts on top and afterwards displays if there already is a Manual Backup and/or a Google Drive Backup (_✓_ or _NOT YET!_ for eachone) (in the future we'll add similar rows for the extra backup options via Dropbox / OneDrive / Baidu / others)
- **screen2 - Backup Wallet** - select backup method
- only BACKUP TO GOOGLE DRIVE and BACKUP MANUALLY are available
- display 3 unavailable options: BACKUP TO BAIDU, then BACKUP TO DROPBOX, then BACKUP TO ONEDRIVE (displayed alphabetically, but unavailable)
- depending on the selection, we have a flow for Google Drive Backup and another one for Manual Backup

The BACKUP TO GOOGLE DRIVE flow is:
- **password screen** - the user is prompted to enter it's Moonlet Password (=the password used for the current wallet), as it will also be used for encrypting the wallet
- the screen contains text on top (), then the password input, then the mandatory checkbox _I understand that Moonlet can not recover this password for me_. and the ENCRYPT WALLET button
- **confirm popup** - the user is prompted to confirm the current Google Drive Backup
- after confirmation the extension checks the Google API and asks for user's permission to store data on his drive (one time persmission needed), then makes the backup on the extension's dedicated app folder (unique name + date of creation)
- do we need a unique name for each backup?
- **done screen** - the user goes back to Security screen above where Google Drive Backup is marked as _✓DONE!_ and also an extra snackbar is displayed on bottom: _✓Done! Your Google Drive backup has been confirmed._

The BACKUP MANUALLY flow is:
- **password screen** - the user is prompted to enter it's Moonlet Password
- **reveal secret phrase screen** - the user needs am extra action to reveal the mnemonic phrase
- **confirm screen ** - the user sees the wallet's secret phrase, he can copy it to clipboard (or any other form of personal backup), and he is prompted to CONFIRM MANUAL BACKUP
- **confirm popup** - the user is prompted to confirm the current Manual Backup
- **done screen** - the user goes back to Security screen above where Manual Backup is marked as _✓DONE!_

Visual flow [here](https://sketch.cloud/s/Ddeke/Kvk2vyn/play).