epic: Cortex track delete models on file system

[gabrielle-ong]

Cortex version

1.0.2

Describe the issue and expected behaviour

• Problem: Jan users are used to deleting the model folder, rather than deleting on Jan UI
• Users cannot just remove the /models folder as the backend has to update cortex.db
• We should track the file system and update cortex.db so that no action is required for them

Approaches (@louis-jan & @namchuai to add on)

• Build cortex.db as a quick lookup table, but like caching, we still monitor folder changes for better performance.
• Scan it once on launch in the background
• To propose filescan interval
• Alternative: model has been deleted! -> delete in cortex.db

QA:

• Delete model folder (or specifically model.yml file)
• expected result: cortex models list does not list the model