* Explore: Remove datasource testing on selector
- datasource testing gets in the way of fast query iteration: switching
between datasources can take seconds
- it should not be explore's duty to test datasources in the first place
- removed the concept of datasourceError in Explore, should not be its
concern
- datasource erorrs will express themselves in query errors just fine
- connection errors are still bubbled up
- removed reconnection logic from explore, should not be its concern
- missing labels in loki are still "visible" via an empty label selector
- Loki and Prometheus treated connection errors differently than other
datasources, making sure to pass through the original error message
* Show datasource error in query field for prom/loki/influx
* Removed connection test case, fixed disabled state
* Rerun query on input changes
Added "this.onRunQuery" for update of the input fields so that the panel updates when changed
* typo in comment
changed "fullu" to "fully"
* modified to onBlur for legend, interval
legend and interval (min step) now call for query re-run when they go 'onBlur' instead of 'onChange'
* PromQueryEditor: Updated snapshot
* WIP prometheus editor same in panel
* Dont use panel in plugin editors
* prettiered modified files
* Fix step in external link
* Prevent exiting edit mode when slate suggestions are shown
* Blur behavior and $__interval variable
* Remove unused query controller
* Basic render test
* Chore: Fixes blacklisted import
* Refactor: Adds correct start and end time
