* Add click on explore table cell to add filter to query

- move query state from query row to explore container to be able to set
  modified queries
- added TS interface for columns in table model
- plumbing from table cell click to datasource
- add modifyQuery to prometheus datasource
- implement addFilter as addLabelToQuery with tests

* Review feedback

- using airbnb style for Cell declaration
- fixed addLabelToQuery for complex label values