Add hclog adapter and gating to eventer (#1915)

This contains to related things:

1. An adapter allowing an hclog interface to take in information and send them to the eventer
2. A gate on the eventer, which is the analogue to the behavior prior to eventing where we'd ensure logs were not printed prior to the startup information. Without this, plugin logs using the hclog adapter will start showing up too early.

internal/servers/controller/controller.go

@@ -125,7 +125,14 @@ func New(ctx context.Context, conf *Config) (*Controller, error) {
 		}
 	}
 
+	var pluginLogger hclog.Logger
 	for _, enabledPlugin := range c.enabledPlugins {
+		if pluginLogger == nil {
+			pluginLogger, err = event.NewHclogLogger(ctx, c.conf.Server.Eventer)
+			if err != nil {
+				return nil, fmt.Errorf("error creating host catalog plugin logger: %w", err)
+			}
+		}
 		switch enabledPlugin {
 		case base.EnabledPluginHostLoopback:
 			plg := pluginhost.NewWrappingPluginClient(pluginhost.NewLoopbackPlugin())
@@ -145,6 +152,7 @@ func New(ctx context.Context, conf *Config) (*Controller, error) {
 					pluginutil.WithPluginExecutionDirectory(conf.RawConfig.Plugins.ExecutionDir),
 					pluginutil.WithPluginsFilesystem(host_plugin_assets.HostPluginPrefix, host_plugin_assets.FileSystem()),
 				),
+				external_host_plugins.WithLogger(pluginLogger.Named(pluginType)),
 			)
 			if err != nil {
 				return nil, fmt.Errorf("error creating %s host plugin: %w", pluginType, err)