fix: add rate limiting to account details update operation

[edward-ly]

Currently, the default rate for this is approximately once every minute, which should be sufficient enough for our needs.

[oleksandr-nc]

Can we add a separate "change_email": "3/h/user" to the ACCOUNT_RATE_LIMITS ?

And in the views.py file we can add ratelimit to the AccountView's form_valid after the comparsions of the emails.

What do you think about such approach CONs and PROs?

And it will be good to have a separate file with tests for this, like:

Scenario 1: Normal account update WITHOUT email change
Scenario 2: Normal email change (within rate limit)
Scenario 3: Email change blocked after exceeding rate limit
Scenario 4: User.email must NOT change when rate-limited
Scenario 5: Name changes still save when email is rate-limited
Scenario 6: Rate limit is independent from reset_password
Scenario 7: Invalid form (wrong password) does NOT consume rate limit
Scenario 8: Same email (no change) does NOT consume rate limit