Initial alpha datasource that saves data directly in a panel or in the shared datasource configs.

Temporarily expose getBackendSrv while we figure out a long term solution.  This will unblock developing some more complex react external plugins.

For react panels the scopedVars did not contain the built in __interval and __interval_ms
variables.

Fixes #16546

Progress: #14714

Closes #15889

CloudWatch: Fix template variable issues 

* fix cloudwatch color order

* fix test

* use for-of

* app pages

* app pages

* workign example

* started alpha support

* remove app stuff

* show warning on alpha/beta panels

* put app back on plugin file

* fix go

* add enum for PluginType and PluginIncludeType

* Refactoring and moving settings to plugins section

fixes #16529

This reverts commit 44b36502.

moved page-action-bar to top and put header inside it, removed </input> to be able to run prettier

While converting this to React we missed subscribing to errors

Fixed #16512

fixes go vet issue that 1.12.3 detects 

Fixes #16501

Fixes #16507

Markdown formatting in VS Code converts from asterisks to underscores but this can be incorrect
in a case like _label_names()_. This fix escapes the underscores that should be kept.

Fixes: #16490

Fixes: #16485

Adds filebeat (log collector) to elasticsearch v6 docker block that 
collects Grafana logs.
Also adds a new elasticsearch v6 datasource and test dashboard 
thru provisioning.

* auto load

* update comments

* gofmt

* use preload from json

* fix formatting

* change general plugin loader to app

* Refactoring: Plugin preloading #15266

Add getQueryDisplayText() to DataSourceApi

* add some types on graph

* set some types in graph

* Fixed typings

* Unprovision dashboard in case of DisableDeletion = true

* Rename command struct

* Handle removed provision files

* Allow html in confirm-modal

* Do not show confirm button without onConfirm

* Show dialog on deleting provisioned dashboard

* Changed DeleteDashboard to DeleteProvisionedDashboard

* Remove unreachable return

* Add provisioned checks to API

* Remove filter func

* Fix and add tests for deleting dashboards

* Change delete confirm text

* Added and used pkg/errors for error wrapping

* show title in singlestat2

* show title in gauge

* use CSS class for emotion

* use emotion not scss

* Fix use of "monotonically" in explore documentation

* Fix use of "monotonically" in query hints and tests

Fixes #16378