Documentation for the new Explore feature.

Describes both the Prometheus-specific features and the
Loki (logging) features.

Explore: Parse initial dates

Explore: Logging line parsing and field stats

Explore: graphInterval needs to update after query execution 

- parse dates passed from URL
- keep everything local time for now

Prometheus: Make result transformer more robust for empty responses

- some prometheus-compatible backends may return `null` instead of empty lists
- test for lists before iterating
- added tests for empty responses

Fix quota updating

Lazily parse lines and display stats for field when clicked on.

- log line parsers for JSON (basic), and logfmt
- delayed parsing in case user moves to other line
- reuse label stats for field stats

Pickers with min-width instead of width

Explore logs styling

Multi button group

Explore: improve error handling

Improve PostgreSQL Query Editor if using different Schemas

more detailed error message for loki

improve light theme look

use new toggle button group in logs

stop propagation on click event

clean up styles

improve support for small when a label is present

refactoring - move toggle button to the group file. turn it into a stateless component

improve support for light theme

rename dedupe to dedup

use radius variable

remove not used code

cleanup

Explore logs css refactor

if grafana tries to access loki without promtail running
it will return an error.

UserPicker and TeamPicker should use min-width instead of fixed widths to avoid overflowing form buttons.  #14341

fixed logs to time series calculation issue, increased bucket size

Rename Grafana Logging Datasource to Loki