Update copy when deleting passwords to consider whether sync enabled or not

[CDRussell]

Task/Issue URL: https://app.asana.com/0/488551667048375/1206638124888258/f

Description

Copy changes around deleting passwords (now showing a different message when sync is enabled vs disabled).

Translations will come in #4446

Steps to test this PR

Sync Disabled

single saved password

• Disable sync (or leave it disabled if off already)
• Visit password management screen (overflow -> passwords)
• Add a single saved password (so you only have 1 total).
• Return to password management screen
• Then choose overflow -> Delete All Passwords
• Verify the dialog title is Are you sure you want to delete this password?
• Verify the dialog message says "password" (singular) and "account" (singular)
• Verify the dialog message says it'll be "deleted from this device"
• Cancel the prompt. Click on the overflow of the saved password, and choose Delete. Ensure the last two checks you just did are still valid for this scenario.

multiple saved passwords

• Add a second saved password (so you now have 2 total), and return to password management screen
• Then choose overflow -> Delete All Passwords
• Verify the dialog title is Are you sure you want to delete 2 passwords
• Verify the dialog message says "passwords" and "accounts"
• Verify the dialog message says it'll be "deleted from this device"

Sync Enabled

multiple saved passwords

• Enable sync
• Visit password management screen (overflow -> passwords). Ensure you have > 1 saved password.
• Then choose overflow -> Delete All Passwords
• Verify the dialog title is Are you sure you want to delete 2 passwords
• Verify the dialog message says "passwords" and "accounts"
• Verify the dialog message says it'll be "deleted from all synced devices"

single saved password

• Enable sync
• Visit password management screen (overflow -> passwords). Ensure you have exactly 1 saved password.
• Then choose overflow -> Delete All Passwords
• Verify the dialog title is Are you sure you want to delete this password?
• Verify the dialog message says "password" (singular) and "account" (singular)
• Verify the dialog message says it'll be "deleted from all synced devices"

[CDRussell]

• Translations for new delete-passwords copy #4446
• Update copy when deleting passwords to consider whether sync enabled or not #4445 👈
• develop

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[cmonfortep]

lgtm, but leaving some comments about naming and asking to move the sync method call to background. I will go through the test cases when the background part is done so it's final. But those are the only 2 things I've seen.

[CDRussell]

@cmonfortep moved sync check to background thread and renamed string builder functions. ready for review. (can ignore the lint error since that'll be solved in the translations branch for this)

[CDRussell]

@cmonfortep pinging for re-review

Note, I had to change how we differentiate between singular and plural cases. Before, got caught out with the "implied plural" lint warnings. So now we check in code if number of elements == 1 and use a normal string if so, and else grab the plural form.

[cmonfortep]

LGTM