MM-28861 Marketplace feature flags (#16451)

* Installing plugins specified by feature flags using the marketplace.

* Switch back to using getplugins client.

* Respect disabling automatic installation of pluings.

* pluginid -> plugin_id

* Debug logs for enable plugin error

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/helper_test.go

@@ -56,6 +56,7 @@ func setupTestHelper(dbStore store.Store, enterprise bool, includeCacheLayer boo
 	}
 	*config.PluginSettings.Directory = filepath.Join(tempWorkspace, "plugins")
 	*config.PluginSettings.ClientDirectory = filepath.Join(tempWorkspace, "webapp")
+	*config.PluginSettings.AutomaticPrepackagedPlugins = false
 	*config.LogSettings.EnableSentry = false // disable error reporting during tests
 	*config.AnnouncementSettings.AdminNoticesEnabled = false
 	*config.AnnouncementSettings.UserNoticesEnabled = false