Implement autocomplete's Login

[mshin-wolvic]

• WolvicPasswordManagerClient for Login save
• WolvicPasswordStorageBackend for Login DB
• WolvicAutofillClient for autofill username/password
• WolvicSignClient is dummy class to avoid crash issue
• Changed components/autofill not to show suggestions of login whenever text field is changed.
• Own Wolvic.pak for resources instead of content_shell.pak to include resources in components
• WolvicRenderFrameObserver for binding Autofill Agent's mojo

[mshin-wolvic]

• I'm a bit scared of adding so much amount of code (even knowing that there are many dummy implementations). Can't we just inherit from another existing clients?

Unfortunately, password manager component has Stubxxx, Mockxxx for test only and there is no inheritable client.

• I don't have a clear idea of how all the actors interact in this whole process, it'd be nice if you could write some brief document explaining how all this work.

OK, I will share the document.

• What's the "crash issue" that forces us to implement the WolvicSignClient?

We don't actually use Identity or Signin of Chromium components, but PasswordManager is tightly close to them without null check. So when this is null, it crashes.

See code here.

void AccountFetcherService::Initialize(
...
  repeating_timer_ = std::make_unique<signin::PersistentRepeatingTimer>(
      signin_client_->GetPrefs(), AccountFetcherService::kLastUpdatePref,

https://source.chromium.org/chromium/chromium/src/+/main:components/signin/internal/identity_manager/account_fetcher_service.cc;l=103?q=AccountFetcherService::Initialize&ss=chromium%2Fchromium%2Fsrc

This will only go through initialization and will no longer work, but we should provide a dummy client to avoid null access.

[mshin-wolvic]

OK, I will share the document.

• What's the "crash issue" that forces us to implement the WolvicSignClient?