v1.19.0

• add capability to ingest document from a URL (@mattlindsey)
• add context window length property to model config (@oxaroky02)
• add settings page
• add toggle in the UI to hide conversations that were created via API
• add ability to search entity descriptions on entity page
• add paging for descriptions on graph entity show page
• move new document form to separate page
• add entity extraction model setting to collection
• add "regenerate message" button
• show whitespace in augmentations in conversation
• add background images to login page
• admin UI improvements
• show error message for collections on job retry exhaustion
• add chunks request spec
• add /v1/conversations/:id/messages
• add /v1/conversations index and show
• automate api testing
• UI tweaks
• code cleanup