Resolve "Improve token usage for users"

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Resolves to #378

controller/northbound/server/auth_test.go

@@ -300,7 +300,8 @@ func TestAuth_addTokenAndEnsureTokenLimit_addKey(t *testing.T) {
 	config.MaxTokensPerUser = 2
 	userID := uuid.New()
 	user := rbac.NewUser(userID, "testUser", map[string]string{}, "password", []string{"token1"}, "salt", conflict.Metadata{ResourceVersion: 0})
-	addTokenAndEnsureTokenLimit(user, "token2")
+	err := addTokenAndEnsureTokenLimit(user, "token2")
+	assert.Nil(t, err)
 
 	assert.Equal(t, 2, len(user.GetTokens()))
 	assert.Equal(t, "token1", user.GetTokens()[0])
@@ -311,7 +312,8 @@ func TestAuth_addTokenAndEnsureTokenLimit_removeOldKey(t *testing.T) {
 	config.MaxTokensPerUser = 2
 	userID := uuid.New()
 	user := rbac.NewUser(userID, "testUser", map[string]string{}, "password", []string{"token1", "token2"}, "salt", conflict.Metadata{ResourceVersion: 0})
-	addTokenAndEnsureTokenLimit(user, "token3")
+	err := addTokenAndEnsureTokenLimit(user, "token3")
+	assert.Nil(t, err)
 
 	assert.Equal(t, 2, len(user.GetTokens()))
 	assert.Equal(t, "token2", user.GetTokens()[0])