Fix profile update spam

[khaitruong922]

• User can request profile update without limits.
• This will cause multiple avatar files created inside Firebase Storage.

TODO:

• Update request limit?
• Delete old avatar?

[chungquantin]

Basically, for this issue, we can do:

• Get the latest update time from the user and if it is under a specific time, we won't allow it.
• Google usually stores all of data and set the expire time