api/types/system: move SecurityOpt type and DecodeSecurityOptions to client

This change moves the `system.SecurityOpt` type and `system.DecodeSecurityOptions` function to the client and adds a set of unit tests to capture current implementation. This change also create a set of daemon backend copies for usage.

Signed-off-by: Austin Vazquez <austin.vazquez@docker.com>

api/types/system/security_opts.go

@@ -1,48 +0,0 @@
-package system
-
-import (
-	"errors"
-	"fmt"
-	"strings"
-)
-
-// SecurityOpt contains the name and options of a security option
-type SecurityOpt struct {
-	Name    string
-	Options []KeyValue
-}
-
-// DecodeSecurityOptions decodes a security options string slice to a
-// type-safe [SecurityOpt].
-func DecodeSecurityOptions(opts []string) ([]SecurityOpt, error) {
-	so := []SecurityOpt{}
-	for _, opt := range opts {
-		// support output from a < 1.13 docker daemon
-		if !strings.Contains(opt, "=") {
-			so = append(so, SecurityOpt{Name: opt})
-			continue
-		}
-		secopt := SecurityOpt{}
-		for _, s := range strings.Split(opt, ",") {
-			k, v, ok := strings.Cut(s, "=")
-			if !ok {
-				return nil, fmt.Errorf("invalid security option %q", s)
-			}
-			if k == "" || v == "" {
-				return nil, errors.New("invalid empty security option")
-			}
-			if k == "name" {
-				secopt.Name = v
-				continue
-			}
-			secopt.Options = append(secopt.Options, KeyValue{Key: k, Value: v})
-		}
-		so = append(so, secopt)
-	}
-	return so, nil
-}
-
-// KeyValue holds a key/value pair.
-type KeyValue struct {
-	Key, Value string
-}