Custom Operators for Filters

We cannot use filtering expressions beyond the predefined ones from cube (equals, contains, etc)

We want to be able to filter based on "ancestor of", as we are querying on a table that utilizes postgres' [ltree functionality](https://www.postgresql.org/docs/current/ltree.html). This operator can be represented as ' @>'. Or, even better would be the ability to use any custom operator.

We need to pass dynamic parameters to our queries, which is why we are unable to use segments instead of filters.