Improve Search

[bedeho]

Basically support these

• Idea: Improve Search atlas#5919
• Operator controlled global search keyword blacklist #53

There is a search feature included in Recombee, which we are implementing, but I'm not sure how well it aligns with our goals here, as it is focused on personalization and also may not have access to all the information we care about, and also not clear how well the text matching works there.