* feat(tql): add initial support for start,stop,step as sql functions
* fix(tql): remove unwraps, adjust fmt
* fix(tql): address taplo issue
* feat(tql): update parse_tql_query logic
* fix(tql): change query parsing logic to use parser instead of delimiter
* fix(tql): add timestamp function support, add sqlness tests
* fix(tql): add lookback optional param for tql eval
* fix(tql): adjust tests for now() function
* fix(tql): introduce the tqlerror to differentiate failures on parsing, evaluation and simplification stages
* fix(tql): add tests for explain/analyze
* feat(tql): add lookback support for explain/analyze, update tests
* feat(tql): add more sqlness tests
* chore(tql): extract common logic for eval, analyze and explain into a single function
* feat(tql): address CR points
* feat(tql): use snafu for tql errors, add more docs
* feat(tql): address CR points