fix(plugins): report metrics for all plugin types, not only MetadataAgents (#4303)

- Add ErrNotImplemented error to plugins/api package with proper documentation
- Refactor callMethod in wasm_base_plugin to use api.ErrNotImplemented
- Improve metrics recording logic to exclude not-implemented methods
- Add better tracing and context handling for plugin calls
- Reorganize error definitions with clear documentation

plugins/api/errors.go

@@ -3,6 +3,10 @@ package api
 import "errors"
 
 var (
-	ErrNotFound       = errors.New("plugin:not_found")
+	// ErrNotImplemented indicates that the plugin does not implement the requested method.
+	// No logic should be executed by the plugin.
 	ErrNotImplemented = errors.New("plugin:not_implemented")
+
+	// ErrNotFound indicates that the requested resource was not found by the plugin.
+	ErrNotFound = errors.New("plugin:not_found")
 )