[varunj-msft]

Description

Stacked on #4050. This PR's own changes: varunj-msft/PyRIT@varunj-msft/13178-Refuse-Saved-Converter-Scorer-Credentials...varunj-msft/13178-Save-Converters-Scorers

This is one of the changes for saving Registry entries across restarts. It builds on #4050, which refuses saved converters and scorers that would use this server's credentials. Until the earlier PRs merge, the diff here also shows their changes.

A converter or scorer created through the API is gone when the backend restarts. With "persist": true, POST /api/converters and POST /api/scorers now save it the way POST /api/targets does (#4026), so restore brings it back at every start.

• The first commit only moves code. The target save steps go from target_service.py to a shared services/saved_entries.py: turn off the server values an entry would read, refuse what it can't hold or a Temporary entry it uses, write the recipe create-only, register it, and delete the recipe again if registering fails. The owner and not-saveable helpers move to routes/common.py, and TargetOrigin (new in FEAT: Save targets created through the API #4026) becomes RegistryEntryOrigin. Targets behave as before.
• persist on converters and scorers follows the target rules. It needs register and a name matching ^[a-z][a-z0-9_]{0,63}$ (422 otherwise). A refusal is a typed 400 (/errors/not-saveable), a taken name is 409, and unreadable storage is 503. The owner is recorded as for targets.
• A saved converter or scorer may only use saved or configuration entries. A reference left out of the request but filled from the configured default values (@apply_defaults) is written into the recipe by name, each entry of a list included, so restore uses the same entries even if nothing sets that default at the next start. A default that is Temporary, or isn't a registered entry, is refused. Other configured defaults apply again from the configuration at every start, as they do for startup entries.
• A converter to save can't take an uploaded file yet, and is built without file parameters, as restore builds it. A type that needs a file says so. A copy made with source can't be saved yet (422).
• Saving a scorer finds its class and builds it off the event loop, since finding the class can take over a second.
• Converters and scorers now have origin (saved, configuration or temporary) on list, get and create, and the startup entries of all three kinds are marked as configuration.
• DELETE /api/converters/{id} returns 409 for a saved converter, since it would come back from its file at the next start. Temporary and configuration converters are removed as before.
• The scorer name types is now reserved, as it is for targets and converters, since GET /api/scorers/types would hide a scorer with that name.
• The backend README and pyrit_conf.md describe saving converters and scorers.

Not covered:

• Converters that pick randomly without a seed, such as the bijection and policy puppetry ones, come back with a new mapping after a restart, as startup converters do.
• GET /api/scorers/types doesn't say yet why a scorer type can't be saved; saving one refuses it with the reason.
• Saving converters from the GUI is the next PR. Showing who saved a converter or scorer, saving copies, deleting or editing saved entries, and keeping uploaded or Blob files on saved converters come later.