- Query now contains expressions, context, fields, groupBy, sort, aggregate,
isSubquery
- Context (a part of query now) contains source, username, project, group, variables

Instead of segmenting at the GraphQLFilters level, we now
segment the GLQL queries directly with operators and values

chore: simplify lib, Query and Context classes

See merge request !269

Allow supporting a new users() segment for segmenting on users
in addition to time segments.

feat: support upto two dimensions

See merge request !270