crypto: Add a backup_version argument to group session backup methods

[andybalaam]

As outlined in element-hq/element-web#26892 (comment) , pass in the backup version we mean when we call inbound_group_sessions_for_backup and mark_inbound_group_sessions_as_backed_up. This will allow us to switch smoothly to a new backup version when the user asks to reset it, instead of modifying lots of records in our DB when this happens.

Fixes https://github.com/element-hq/crypto-internal/issues/206

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.62%. Comparing base (682c17c) to head (a843125).
Report is 19 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3253      +/-   ##
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- Coverage   83.62%   83.62%   -0.01%     
==========================================
  Files         238      238              
  Lines       24645    24649       +4     
==========================================
+ Hits        20609    20612       +3     
- Misses       4036     4037       +1     

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[poljar]

A bit strange to add an argument that no store uses, but I presume that you have an implementation and did double check that this indeed works as intended.

Left a nit for the changelog, looks good otherwise.

[andybalaam]

A bit strange to add an argument that no store uses, but I presume that you have an implementation and did double check that this indeed works as intended.

My plan is to check it works by implementing in the MemoryStore I'll hold off on merging this until that is done.

[andybalaam]

@poljar if you get time, please could you check the newest commit?

Also, I have questions about the InboundGroupSession::backed_up field, which I plan to discuss in #3306 - any input would be appreciated.

[andybalaam]

I addressed the review comments and made a tiny refactor of the tests, so queuing to merge without additional review.