Query Block: Consider allowing for an optional semantic wrapper tag

[kjellr]

It's possible to use a tagName attribute to specify a wrapper tag for Template Part and Group blocks. This helps enable semantic tags for common use cases like a page <header> or <footer>. This option is not currently available for the Query block, though it might be useful there too.

Sometimes, theme templates will consist of just a header template part, a footer template part, and a query loop in the middle. Semantically, that query should be wrapped in a <main> tag. In other cases, the query should be wrapped in a section tag. The only way to do this currently would be to wrap the query in of a Group block with tagName="main" or tagName="section" set.

This solution is ok, but it might be simpler to allow the Query block to optionally render its own semantic wrapper tags using the same tagName attribute.