feat: support memo filter for mysql and postgres

plugin/filter/converter.go

@@ -0,0 +1,20 @@
+package filter
+
+import (
+	"strings"
+)
+
+type ConvertContext struct {
+	Buffer strings.Builder
+	Args   []any
+	// The offset of the next argument in the condition string.
+	// Mainly using for PostgreSQL.
+	ArgsOffset int
+}
+
+func NewConvertContext() *ConvertContext {
+	return &ConvertContext{
+		Buffer: strings.Builder{},
+		Args:   []any{},
+	}
+}