Make rendering work when using serve_from_sub_path and not have rendering.renderer_url configured.

Fixes #21925

* UI: Adds option to limit number of visible selected options to Select component

grafana-plugin-model is legacy and is replaced by new backend 
plugins SDK and architecture. Renderer is not part of SDK and 
we want to keep it that way for now since it's highly unlikely there 
will be more than one kind of renderer plugin.
So this PR adds support for renderer plugin v2.
Also adds support sending a Device Scale Factor parameter to the 
plugin v2 remote rendering service and by that replaces #22474.
Adds support sending a Headers parameter to the plugin v2 and
remote rendering service which for now only include 
Accect-Language header (the user locale in browser when using 
Grafana), ref grafana/grafana-image-renderer#45.
Fixes health check json details response.
Adds image renderer plugin configuration settings in defaults.ini 
and sample.ini.

Co-Authored-By: Arve Knudsen <arve.knudsen@gmail.com>

* Small update proposal to add panel widget

* Fix smoketest

* Minor tweaks

* update snaps god damn it

* FormField to LegacyForms

* FormLabel to InlineFormLabel

* Move SecretFormField to LeagcyForms

* Fix sign in button

* Fix modal button in button

* Add width property

* Remove unused import

* Spelling mistake

* Add width to interface

* Make width optional

* Remove size

* Update snapshot

* Remove size from places

* Add size prop for button

* Update width

* Update snapshots

* regenerated packages docs.

* fixed spelling issues.

* fixed spelling issues.

* InputDatasource: Fixed prettier errors

* Fixed prettier config in toolkit to make it consistent with grafana core prettier config

* CSS: Various css bug fixes

* Updated

* Move visualisation picker to the sidebar pane

* Remove vis tab from bottom pane

* Visualisation to panel type title

* Search: Toggle Search based on search query

* Search: Fix types and closed search param

* Search: Remove appEvents from SearchWrapper

* Search: Reset folder on close

Co-Authored-By: Alexander Zobnin <alexanderzobnin@gmail.com>

* Search: Disable reloadOnSearch for manage dashboards urls

Co-authored-by: Alexander Zobnin <alexanderzobnin@gmail.com>

Co-Authored-By: Arve Knudsen <arve.knudsen@grafana.com>
Co-Authored-By: Leonard Gram <leonard.gram@grafana.com>

* Add uid to datasource

* Fix uid passing when provisioning

* Better error handling and Uid column type change

* Fix test and strict null error counts

* Add backend tests

* Add tests

* Fix strict null checks

* Update test

* Improve tests

* Update pkg/services/sqlstore/datasource.go

Co-Authored-By: Arve Knudsen <arve.knudsen@gmail.com>

* Variable rename

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>

* Drawer: add subtitle, expandable button and refactor style

* Drawer: update header style and z-index

* Drawer: refactor Drawer component and PanelInspector

* PanelInspector: add expandable

* Drawer: update stories with new props

* Inspector: rename InspectHeader -> InspectSubtitle

* Inspector: fix tabs spacing

* Drawer: remove z-index

* Update public/app/features/dashboard/components/Inspector/InspectSubtitle.tsx

Co-Authored-By: Dominik Prokop <dominik.prokop@grafana.com>

* Drawer: apply PR feedbacks

Co-authored-by: Dominik Prokop <dominik.prokop@grafana.com>

* Error handling for setObject to store

* Update public/app/core/store.ts

Co-Authored-By: kay delaney <45561153+kaydelaney@users.noreply.github.com>

* Update public/app/features/explore/RichHistory/RichHistory.tsx

Co-Authored-By: kay delaney <45561153+kaydelaney@users.noreply.github.com>

* Move setState outside of try-catch block

Co-authored-by: kay delaney <45561153+kaydelaney@users.noreply.github.com>