Adding presence query to the search bar

The search bar's regexes currently support 3 type of queries:

• equality
• simple LTE/GTE
• sandwiched LTE/GTE

I would argue that at least a 4th one applies: the presence query, which consists simply out of the quantity / section name and checks its existence. In the filter side menu this is already supported. Examples include all of the methods ("DFT", "GW", "BSE") as well as properties like "Electronic".

Being able to compose / stack queries inline (via and, or) would also be nice, but less pressing.