* adds +/- buttons to query rows in the Explore section
* on Run Query all query expressions are submitted
* `generateQueryKey` and `ensureQueries` are helpers to ensure each
 query field has a unique key for react.

prometheus: variable query should fallback correctly to a series query 

sql tsdb: fix value columns conversion to float when using timeseries query

fix misalignment of unit and other drop downs in firefox

removed height 100% from panel-container to fix ie11 panel edit mode

Add weback-dev-server with hot/hmr support

Using a query of for example up or up{job=job1}

Add silent option to backend requests

Added requests/sec(throughput)

allow to show more preview values for variables

fixed so user who can edit dashboard can edit row

Fix ineffassign issues

From review feedback:

* s/helper/metadata
* combined positional args to _request into options dict
* metadataRequest reuses _request()
* moved consumption of this.httpMethod into _request, can be overwritten
 in options due to spread-after

* loadStore() modified the url which triggered a new render path, this
gets noticed by react. Moved to componentDidMount.

Signing was failing as the builds
were expected to run as ubuntu but
is run as root.

Closes #11686

Make Ldap group composed of  DNs work.