Edits to the Datasets tab

[semihsalihoglu-uw]

I was playing around with Explorer and realized that now that we have an Import Data tab, we should be more clear in the message we have in Datasets tab. These two tabs are confusing. I think it's easy to think that "Datasets" is a tab that shows your imported CSV/parquet files.

I think the ideal solution would be to merge these inside "Import Data". On the left panel of Import Data, i.e., the "+Add More Files" column, below could be "Bundled Datasets", which have a separate button to load them. This part could be disabled/gray with a warning if you already have created a manual database.

But for now, we could also do a very minor change to modify the warning message when you go to "Datasets" tab: " You have already loaded a database. You can still review the schema of the bundled datasets. If you want to load a different dataset, please restart your Kùzu Explorer Docker image with an empty database or drop all tables in the current database." to something like: "This panel is to create a database from bundled files. You have already created your own database. You can still review the schema of the bundled datasets. If you want to load a bundled dataset, please restart your Kùzu Explorer with an empty database or drop all tables in the current database."