Database: a few little things to improve usability

Description of the issue

The "database" page itself may be enhanced to help new users to navigate / understand it better. I make a few suggestions below.

Ideas of solution

• Add an (i) next to View my tables and explain what that actually means.
• Change the text behind the (i) next to filters to: You can search for text that may occur in table names and metadata using the searchbar. Using the dropdown menu you can filter for one or multiple Tags, and only topics containing tables with all selected Tags will be displayed. You can also combine text and tag search. To see all schemas and tables again use the reset filter button. (like this the (i) text refers to information from left to right, as we read).
• New Tags: does it make sense to have this on the main database page or any overview page that is? Isn't it sufficient to have this when adding tables or working on them?
• OEMetadataBuilder: same as for "New tags"
• Add a data set: add an (i) next to it to explain what happens when you click this and why it is located only under topic model_draft. Also - when you click it the wizard opens without much ado. The wizard could also profit from a short introductory text, so users know what this interface is about.

Workflow checklist

• I am aware of the workflow in CONTRIBUTING.md