Dash previews: populate crawler queue from SQL query (#44083)

* add SQL migrations

* dashboard previews from sql: poc

* added todos

* refactor: use the same enums where possible

* use useEffect, always return json

* added todo

* refactor + delete files after use

* refactor + fix manual thumbnail upload

* refactor: move all interactions with sqlStore to thumbnail repo

* refactor: remove file operations in thumb crawler/service

* refactor: fix dashboard_thumbs sql store

* refactor: extracted thumbnail fetching/updating to a hook

* refactor: store thumbnails in redux store

* refactor: store thumbnails in redux store

* refactor: private'd repo methods

* removed redux storage, saving images as blobs

* allow for configurable rendering timeouts

* added 1) query for dashboards with stale thumbnails, 2) command for marking thumbnails as stale

* use sql-based queue in crawler

* ui for marking thumbnails as stale

* replaced `stale` boolean prop with `state` enum

* introduce rendering session

* compilation errors

* fix crawler stop button

* rename thumbnail state frozen to locked

* #44449: fix merge conflicts

* #44449: remove thumb methods from `Store` interface

* #44449: clean filepath, defer file closing

* #44449: fix rendering.Theme cyclic import

* #44449: linting

* #44449: linting

* #44449: mutex'd crawlerStatus access

* #44449: added integration tests for `sqlstore.dashboard_thumbs`

* #44449: added comments to explain the `ThumbnailState` enum

* #44449: use os.ReadFile rather then os.Open

* #44449: always enable dashboardPreviews feature during integration tests

* #44449: remove sleep time, adjust number of threads

* #44449: review fix: add `orgId` to `DashboardThumbnailMeta`

* #44449: review fix: automatic parsing of thumbnailState

* #44449: lint fixes

* #44449: review fix: prefer `WithDbSession` over `WithTransactionalDbSession`

* #44449: review fix: add a comment explaining source of the filepath

* #44449: review fix: added filepath validation

* #44449: review fixes https://github.com/grafana/grafana/pull/45063/files @fzambia

Co-authored-by: Ryan McKinley <ryantxu@gmail.com>
Co-authored-by: Alexander Emelin <frvzmb@gmail.com>

pkg/models/theme.go

@@ -0,0 +1,20 @@
+package models
+
+import "errors"
+
+type Theme string
+
+const (
+	ThemeLight Theme = "light"
+	ThemeDark  Theme = "dark"
+)
+
+func ParseTheme(str string) (Theme, error) {
+	switch str {
+	case string(ThemeLight):
+		return ThemeLight, nil
+	case string(ThemeDark):
+		return ThemeDark, nil
+	}
+	return ThemeDark, errors.New("unknown theme " + str)
+}