Function createGroupMessagesProvider

createGroupMessagesProvider(deps: ProviderDeps): MessagingProvider
The group provider: group sessions whose shared keys move on with every change to the group, so a leaked key reveals neither earlier messages nor, once the group moves on, later ones. Experimental; every member needs an app that supports it. Specified by the Marmot protocol (MLS, RFC 9420, over Nostr), which supersedes NIP-EE.
Parameters
- deps: ProviderDeps
  Backend constructor and availability check supplied by the shell.
Returns MessagingProvider
A MessagingProvider with id group.
Example
```
registry.register(createGroupMessagesProvider({
  createBackend: () => groupAdapter,
  available: () => ({ available: true }),
}));
```