This commit removes the one remaining (known) difference with the sysdig
c++ parser: relational expression right-hand sides now _only_ need to be
quoted if they contain a paren or a space.

So you can now do things like "fd.name contains (.log and event.dir = <"
without needing to quote "*.log" or "<".

For example, `a.b in [1, 2]` is expanded to `a.b = 1 or a.b = 2`.
This is done over the AST, not filter text.