Organize backend into product executable and shared Go modules

backend/product/sessions/store/fields.go

@@ -0,0 +1,11 @@
+package refreshtokens
+
+const (
+	ExpiresAtField      = "expiresAt"
+	IsRevokedField      = "isRevoked"
+	TokenField          = "token"
+	UserAgentField      = "userAgent"
+	IPAddressField      = "ipAddress"
+	LastUsedAtField     = "lastUsedAt"
+	SessionVersionField = "sessionVersion"
+)