Add support for inline image uploads to telegram notifier plugin

If image upload is enabled, but there is no public image repository,
fall back to sending an image via telegram's API.

This is a pre-requisite for uploading inline images.

Fixes #10472

* dashboard: repeat rows and panels tests

* fix variable values passing when both repeat rows and panels is used

* Add eu-west-3 as a possible default datasource

* Add eu-west-3 as a possible default datasource

* poc: Use react-popper for tooltips #10389

* poc: Add popover component and use a hoc() for Tooltip + Popover to avoid code duplication #10389

* jest: Add snapshot tests to Popover and Tooltip #10389

* poc: Move target from hoc into Popover/Tooltip-component #10389

* poc: Clean up unused styles and use the existing Grafana style/colors on popper tooltip #10389

* poc: Remove test code before PR

* poc: Remove imports used in poc but shouldn't be included anymore #10389

* ux: When adding a new panel we should scroll to top until we figure out a better solution #10299

* ux: Use jquery to add smooth scrolling when scrolling up to add a panel, and make sure to pass the scope to the event emitter, #10299

* ux: Add a close button to the "New panel"-box and make sure you scroll to top every time you click "Add panel" #10299

Incorrect return values in onbeforeunload event handler mean that the
unsaved changes popup is shown despite there being no changes.

* Add nginx proxy docker container

Ease test/verification of running Grafana thru a reverse proxy

* Add apache proxy docker container

Ease test/verification of running Grafana thru a reverse proxy

* Fix relative urls for reset password page

* Fix relative urls for signup page

* Fix relative urls for login page

* Fix relative urls edit plugin page