Added support to block/unblock contacts and receive block/unblock events

[emacielxp]

Block/Unblock support

Added support to block/unblock contacts and receive block/unblock events

Changes:

connectionevents.go

• Sync at the local database the blocked list when successfully connect

mdtest/main.go

• Included commands to test the block/unblock feature:
  -- listblocked: get the blocked list from whatsapp
  -- syncblockedlist: get the blocked list from whatsapp and update local database
  -- block: block contact
  -- unblock: unblock contact

• Included contact blocked status changed event listener

notification.go

• Included function to handle the whatsapp block/unblock event changes

store/sqlstore/store.go

• Included queries to update database contact block column

• Included functions to use the above queries

• Change getContact and GetAllContacts functions to return the blocked flag inside the ContactInfo data

store/sqlstore/upgrade.go

• Included a new upgrade database function with the alter table with the new column related to the blocked flag

store/store,go

• Included functions created at: store/sqlstore/store.go

types/events/events.go

• Created the contact blocked status changed event type definition

types/user.go

• Changed the ContactInfo included the Blocked field

user.go

• Created necessary functions to allow list, block and unblock contacts

Notes:

this feature was already tested and works fine at:

• iphone business
• iphone normal
• android business
• android normal

[tulir]

Not sure if it should be stored in the db, might be better to just have the methods for modifying and fetching the list and event types for incoming notifications

[emacielxp]

i've do this because in some cases my system send messages for blocked contacts and whatsapp return 403 error, but at whatsapp app or whatsapp web you can't send messages when the contact is blocked and i think this may cause problems with whatsapp to clients that use my system (because sending messages that isn't allowed for blocked contacts at official channels)..

i've implemented before i send a message (call SendMessage function) to check at the local database (GetContact function) if the contact is blocked or not and skipping sending if blocked, but thinking now, maybe this control (send or not the message) shoud be implemented inside the whatsmeow SendMessage function, to avoid the problem i mentioned before..

i will do this refactor and update this PR

[emacielxp]

according your reply, removed from database the store of contact block data, create a blocked contact memory cache similar to groupParticipantsCache and validate at sendMessage function to return an error when the contact is blocked

[emacielxp]

@tulir any news about this PR?

[salman0ansari]

tested this PR and code is working fine
I wonder why it has not been merged yet

[emacielxp]

I will open a new PR with this feature

[mateusfmello]

I will open a new PR with this feature

@emacielxp if possible, enter the URL of the new PR here.

I'm waiting for the merge of this feature.

[emacielxp]

@mateusfmello here is: #460