PublicDashboards: Add setting to disable the feature (#78894)

* Replace feature toggle with configuration setting

* Fix permission alert

* Update documentation

* Add back feature toggle

* revert unwanted commited changes

* fix tests

* run prettier

* Update SharePublicDashboard.test.tsx

* fix linter and frontend tests

* Update api.go

* Apply docs edit from code review

Co-authored-by: Isabel <76437239+imatwawana@users.noreply.github.com>

* Update index.md

* Update docs/sources/setup-grafana/configure-grafana/feature-toggles/index.md

Co-authored-by: Agnès Toulet <35176601+AgnesToulet@users.noreply.github.com>

* Update docs/sources/setup-grafana/configure-grafana/_index.md

Co-authored-by: Agnès Toulet <35176601+AgnesToulet@users.noreply.github.com>

* add isPublicDashboardsEnabled + test

* fix test

* update ff description in registry

* move isPublicDashboardsEnabled

* revert getConfig() update

---------

Co-authored-by: Isabel <76437239+imatwawana@users.noreply.github.com>
Co-authored-by: Christopher Moyer <35463610+chri2547@users.noreply.github.com>

pkg/setting/setting.go

@@ -541,6 +541,9 @@ type Cfg struct {
 	// sqlstore package and HTTP middlewares.
 	DatabaseInstrumentQueries bool
 
+	// Public dashboards
+	PublicDashboardsEnabled bool
+
 	// Feature Management Settings
 	FeatureManagement FeatureMgmtSettings
 }
@@ -1254,6 +1257,7 @@ func (cfg *Cfg) Load(args CommandLineArgs) error {
 	cfg.UserFacingDefaultError = logSection.Key("user_facing_default_error").MustString("please inspect Grafana server log for details")
 
 	cfg.readFeatureManagementConfig()
+	cfg.readPublicDashboardsSettings()
 
 	return nil
 }
@@ -1965,3 +1969,8 @@ func (cfg *Cfg) readLiveSettings(iniFile *ini.File) error {
 	cfg.LiveAllowedOrigins = originPatterns
 	return nil
 }
+
+func (cfg *Cfg) readPublicDashboardsSettings() {
+	publicDashboards := cfg.Raw.Section("public_dashboards")
+	cfg.PublicDashboardsEnabled = publicDashboards.Key("enabled").MustBool(true)
+}