Fix a typo in doc about alerting

Fix a typo

Fix invalid time range causes panic in Cloudwatch datasources 

Add ability to toggle visibility of graph series in explore section

updates time range options for alert queries

Fix errcheck issues

add some new options for the to value.
removes '1s' option for from since thats unreasonable low

closes #12134

Adds example timeline in docs for alerting for

Discovered implementation issues with the set utilities used in the
explore section after adding some tests. Added tests to reinforce the
expected behaviour of the utility functions.

Related: #13522

Co-Authored-By: bergquist <carl@grafana.com>

Co-Authored-By: bergquist <carl@grafana.com>

fixed issue with new legend not checking if panel.legend.show

The implemented toggling UX is similar to how the dashboard graph plugin
behaves. Also incorporates review feedback to persist series visibility
state by means of the alias property, with the limitation it carries
too.

Related: #13522

fix for issue with error view in production builds

Stackdriver template query editor

Add basic authentication support to metrics endpoint