Metadata, delete chatbot namespace and other changes.

[lvalics]

• Implemented functionality to delete a chatbot namespace from the vector database, along with all records associated with that chatbot, upon chatbot deletion.
• The Directory Data Loader must be updated to include filename metadata to enable filtering. PR#138
• Enhanced the history log interface to display whether a message has received positive or negative feedback.
• Fixed the title when the page is being crawled; it will now be saved to the database.
• On a deleted document, if the namespace does not exist, do not throw an error; instead, delete the file