Option to suppress/manage "Identity reset" warnings

### Your use case

#### What would you like to do?

I would like to have a configuration option to manage or suppress "Identity reset" warnings. Specifically, it should be possible to
* either make it configurable to suppress this type of warning for a specific chat room
* or provide an option in the user settings to ignore / automatically accept all identity changes from other users
* or let the user dismiss all current warnings at once, rather than closing them one by one.

#### Why would you like to do it?

In large organizations and chat rooms with a large amount of participants, people frequently reset their identity. Each time this happens, the "Identity reset" warning appears:

After a few weeks, this results in hundreds of alerts. You have to click through each one individually to clear them.

#### How would you like to achieve it?

I can think of a few different options:
* A “hide all” option might be easiest to implement at the UI level.
* An option for chat admins to suppress these warninge (for everyone but only for a specific chat room).
* An option for individual users to turn off these warnings (on a per-user basis for all chat rooms).

### Have you considered any alternatives?

_No response_

### Additional context

An organization I belong to has several thousand members. There are group chats on various topics with hundreds of members. It’s not uncommon for someone to need to reset their identity, for example, because they’ve lost their recovery method. On top of that, not everyone is familiar with the technology behind it—specifically, end-to-end encryption. These warnings therefore often lead to confusion and a certain fatigue with security alerts.

No files, tests, or entry points are mentioned. First clarify which of the proposed behaviors is in scope—room-level suppression, user settings, or bulk dismissal—before locating the relevant warning and settings flows; done means the selected behavior is implemented and its security implications are covered.

Written by the indexing model from the issue text.