Plugins: Introduce new Flame graph panel (#56376)

* Flamegraph

* Updated flame graph width/height values

* Fix top table rendering issue

* Add feature toggle for flamegraph in explore

* Update tests

* Hide flamegraph from dash panel viz list if feature toggle not enabled

* Show table if no flameGraphFrames

* Add flame graph to testdata ds

* Minor improvement

pkg/plugins/manager/manager_integration_test.go

@@ -164,6 +164,7 @@ func verifyCorePluginCatalogue(t *testing.T, ctx context.Context, ps *store.Serv
 		"candlestick":    {},
 		"news":           {},
 		"nodeGraph":      {},
+		"flamegraph":     {},
 		"traces":         {},
 		"piechart":       {},
 		"stat":           {},