[sdk#740] Rework sandbox to use tokenTimeout instead of tokenGenerator

[Bolodya1997]

Description

1. Reworks sandbox to set tokenGeneratorSupplier for domain:

// SupplyTokenGeneratorFunc supplies token generator
type SupplyTokenGeneratorFunc func(tokenTimeout time.Duration) token.GeneratorFunc

2. Starts using tokenTimeout instead of tokenGenerator in all New* methods:

// NewNSMgr creates a new NSMgr
func (n *Node) NewNSMgr(
	ctx context.Context,
	name string,
	serveURL *url.URL,
-	tokenGenerator token.GeneratorFunc,
+	tokenTimeout time.Duration,
	supplyNSMgr SupplyNSMgrFunc,
) *NSMgrEntry {

3. Adds DefaultDialOptions for domain:

// DefaultDialOptions returns default dial options for the domain
func (d *Domain) DefaultDialOptions(tokenTimeout time.Duration) []grpc.DialOption {
	return DefaultDialOptions(d.supplyTokenGenerator(tokenTimeout))
}

Issue link

How Has This Been Tested?

• Added unit testing to cover Covered by existing unit testing
• Tested manually
• Tested by integration testing
• Have not tested

Types of changes

• Bug fix
• New functionallity
• Documentation
• Refactoring
• CI

[denis-tingaikin]

I don't think that we need to replace tokenGen function with token timeout in sandbox due to it can be used for advanced OPA policy testing.