Support computed fields that use the hasura_session in query ordering and filtering

Thanks for this! Shouldn't compute fields that use the hasura_session be supported as it's a default there already really?

_Originally posted by @neil-buckley in https://github.com/hasura/graphql-engine/issues/7336#issuecomment-901232888_

The issue names no files, tests, or entry points. Start by locating computed-field handling for query ordering and filtering, then trace how hasura_session is supplied; done means computed fields using it work in both operations with regression coverage.

Written by the indexing model from the issue text.