feat: Update CRUD of session template.

[agatha197]

• Modified to create/update multiple session templates at once
• Fields such as template or domain_name can also be read or updated.
• Correct typo of example-session-templates.json

Related: control-panel#120, webui#1133

[codecov]

Codecov Report

Merging #480 (14ac2bd) into main (15acec7) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #480   +/-   ##
=======================================
  Coverage   48.89%   48.89%           
=======================================
  Files          54       54           
  Lines        8908     8908           
=======================================
  Hits         4356     4356           
  Misses       4552     4552           

Impacted Files	Coverage Δ
src/ai/backend/manager/models/session_template.py	31.64% <ø> (ø)

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[achimnol]

Overall LGTM, but please append trailing commas. 😉

[adrysn]

I tested and it works. LGTM for me.

[achimnol]

Please check whether checking the emptiness of query results is actually executed or not.
I think it should be rewritten to count the number of returned rows instead of performing None-check inside the for-loop against the result.