CSAF: build useful `product_tree`s

[tschmidtb51]

Currently, CSAF documents (e.g. 1 and 2) exist, that do not follow the structure vendor->[product_family->]product_name->product_version

Please update the structure to enable matching, e.g. (assuming the vendor name and versioning scheme here):

    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:intdot/<1.5.374.11",
                "product": {
                  "name": "OPC UA .NET Standard Stack <1.5.374.11",
                  "product_id": "CSAFPID-01"
                }
              }
            ],
            "category": "product_name",
            "name": "OPC UA .NET Standard Stack"
          }
        ],
        "category": "vendor",
        "name": "OPC Foundation"
      }
    ]
  },