Launch import flow from Password management screen

[CDRussell]

Task/Issue URL: https://app.asana.com/0/608920331025315/1208434183978073/f

Description

Adds UI which allows users to access the flow for importing passwords directly from Google Password Manager.

Steps to test this PR

Empty state

• Fresh install
• Visit Passwords screen and verify you see Import Passwords From Google button in the empty state (if WebView version supports it)

Pre-import dialog

• Tap the button, and verify the bottom sheet looks good

Success results dialog

• Tap Open Google Passwords button and complete the flow
• Verify that you see the success dialog confirming how many passwords were imported.

Success results dialog (with duplicates detected)

• [If you didn't see any duplicates in the last step] repeat previous step and verify duplicates are mentioned but not imported

Failure dialog
It's possible the flow couldn't be completed if the user enabled an old setting in GPM to encrypt passwords with a passphrase. Expecting this to be uncommon, but here's how to test the UI if this happens:

• Apply Patch for testing: encrypted with passphrase
• Start the import flow, and you'll see the error page
• Tap the ✖️ button
• Verify the results dialog shows an error state

[CDRussell]

• Launch import flow from Password management screen #5098 👈 (View in Graphite)
• Add custom webview for importing via GPM #5097
• Add ability to support importing passwords from Google as CSV #4601 : 1 other dependent PR (#4602 )
• Add feature flag for importing passwords via Google Password Manager #5096
• develop

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