Fetch messages from store nodes on a scheduled basis

[vitvly]

Problem

We need to fetch messages periodically from store nodes.

Currently this is done by

status-go/protocol/messenger.go

Line 928 in dfdc165

m.asyncRequestAllHistoricMessages()

which is periodically invoked from Messenger.watchConnectionChange():

status-go/protocol/messenger.go

Line 1447 in dfdc165

processNewState(m.Online())

But this won't fetch anything in case there was no connection state change. Moreover, this is not a pure polling mechanism, as same role is fulfilled by the code below, that utilizes waku2's ConnStatusSubscriptions.

UPDATE: clear now, the polling mechanism is only there for deprecated wakuv1. Additionally, wakuv1 also supports mailserver cycle events, that are processed when peers are updated.

So, we need a proper polling mechanism for store node messages.

Proposed solution

1. Write a code that will do the following every N minutes:

• check if we're current in the process of fetching. If so, do nothing.
• otherwise, and if last fetch time was earlier than N minutes, start fetching.

2. Provide a user-configurable setting for N.
3. Chore: drop waku1 code from Messenger.watchConnectionChange().

cc @churik @cammellos

[vitvly]

Respective PR (#5292) closed, some refactorings extracted into #5420.