"query in workspace" action needs some usability improvements

[hamilton]

I love this "query in workspace" action. It needs a few tweaks to be more useful:

• [ ] we should explicitly select all the columns in the model, not select * from tbl. This enables the user to quickly remove things they don't want.
• [x] the language isn't quite right. We're not actually querying the data; we're building a model. "transform this source" is maybe more accurate.
• [x] #652