Group Session Cache inconsistency between IOS main app and Share Extension

[jacotec]

In Element/IOS the encryption is used by the main app and the Share extension running as different processes. This leads to reproducible inconsisteny of the message ID (and I fear sometimes also of the session ID) by using the group session cache.

I've files the bug as element-hq/element-ios#7499 and user @Anderas did a great analysis what's happening.

I have a slight feeling that the root issue might be in the cache handling in this SDK (cache is maybe not multi-process-proof), therefore I file this issue here as well.