Remove or move notification package from go-ethereum fork to status-go

[pedropombeiro]

Problem

According to some comments (here and here), regarding a package which deals with notifications in https://github.com/status-im/go-ethereum/tree/develop/whisper/notifications, it is not clear if this code is required, but at the very least, it is not necessary for this code to live there and it implies patches (https://github.com/status-im/status-go/blob/develop/_assets/patches/geth/0004-whisper-notifications.patch, https://github.com/status-im/status-go/blob/develop/_assets/patches/geth/0013-whisperv6-notifications.patch). Should the code still be needed, it should be moved to the status-go repo.

Implementation

Investigate whether code is needed. Remove it if not, move it to status-go if yes.

Acceptance Criteria

• After removal push notifications work properly.
• Chat performance and functionality is not deteriorated.

Notes

Code that initializes notifications: https://github.com/status-im/status-go/blob/develop/geth/node/node.go#L186-L192

[JekaMas]

The other issue is that the patch contains some useful modifications to whisper service. So it couldn't been removed all at once.
So additional criteria: chats are working fine with the same speed.

[adambabik]

@pombeirp @JekaMas what do you think about splitting 0013-whisperv6-notifications.patch into two patches so that one encapsulates only whisper/notifications/ code and another one Whisper V6 changes? Even if whisper/notifications/ is needed, this issue would not require changing 0013-whisperv6-notifications.patch.

[JekaMas]

That'd be great. It should be in the issue.

[adambabik]

One thing: watch out for not making circular imports. In whisper/whisperv5/whisper.go there is notificationServer NotificationServer attribute. So, we will end up with status-go importing go-ethereum and go-ethereum (after patching) will import status-go to get NotificationServer declaration.