Refactor Credential Provider autofill flow

[Kayla Galway]

Vision statement / What / Requirements

• Credential Provider currently syncs before autofilling a user's credentials

• This results in a slow autofill experience as well as Credential Provider extension timeouts(and no autofill) when sync takes longer than three seconds

• Refactor Credential Provider extension so that we autofill the credential and then fire off a background task to sync so that any updates are made locally for future autofill

Issue Fix ticket for #1070