feat: Added event existence check upon alert creation

[frgfm]

Following up on #146, this PR introduces the following modifications:

• fixed fetch_ongoing_alerts
• made event_id optional in alert creation payloads
• added a check of existing event referred by similar alerts -> if none exists, it creates an event, otherwise takes the latest
• updated client accordingly
• added corresponding unittests

Any feedback is welcome!

[codecov]

Codecov Report

Merging #149 (a8e88d7) into master (21810fd) will increase coverage by 0.34%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #149      +/-   ##
==========================================
+ Coverage   89.98%   90.33%   +0.34%     
==========================================
  Files          28       28              
  Lines         839      859      +20     
==========================================
+ Hits          755      776      +21     
+ Misses         84       83       -1     

Flag	Coverage Δ
unittests	90.33% <100.00%> (+0.34%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/app/api/crud/alerts.py	67.74% <100.00%> (+39.17%)	⬆️
src/app/api/routes/alerts.py	98.14% <100.00%> (+1.92%)	⬆️
src/app/api/schemas.py	99.18% <100.00%> (+<0.01%)	⬆️
src/app/config.py	96.55% <100.00%> (+0.12%)	⬆️
src/app/db/tables.py	100.00% <0.00%> (ø)

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[fe51]

This PR looks good to me as long as it responds to the problem of linking an alert flow to an event !

Thanks for opening it !

[fe51]

By setting media_id optional, an alert can be sent without related media ? (I am just wandering if its related to this PR but why not ! )

[frgfm]

Oh no, this is something that we decided a long time ago 😅 (cf. the SQL table field ;) )
It's for the future case when someone notifies an alert but has no mean to send the picture