[analyzer] Extract the type and category of bug reports

Extract the type and category of bug reports as well from the analyzer plist files

This is based on my observation of such an entry in the plist files:
```
{
  "clang_version" => "..."
  "files" => [
    0 => "..."
  ]
  "diagnostics" => [
    0 => {
      "category" => "..."
      "location" => {
        "col" => 17
        "file" => 0
        "line" => 53
      }
      "path" => [
        0 => {
          "location" => {
            "col" => 17
            "file" => 0
            "line" => 53
          }
          "depth" => 0
          "extended_message" => "xxx'"
          "message" => "xxx'"
          "kind" => "event"
        }
      ]
      "description" => "xxx"
      "type" => "yyy"
    }
  ]
}
```