[Patch] Mute and unmute requests

[KarimNahas]

PR Content:

• Patched incorrect implementation of mute and unmute requests:
  • Incorrect body format
  • Incorrect logic in unmute

[KarimNahas]

@kanata2 I've updated this branch hoping that it could get merged now:

• Changed name of methods from MuteChat and UnMuteChat to MuteConversation and UnMuteConversation.
• Changed signature of methods to return the updated list of muted conversations.
• Added Context variant to the methods namely (GetUserPrefsContext, MuteChatContext and UnMuteChatContext).
• Added tests for MuteConversation and UnMuteConversation.
• Added comments on methods. Let me know if anything else needs to be done.