Add metainfo tags to Elektron sounds

[dagargo]

Elektron Transfer provides the sound tags inside the manifest.json while Elektroid does not provide these.

$ cat manifest.json
{
  "FormatVersion": "1.0",
  "ProductType": [
    "12"
  ],
  "Payload": "HUMAN SOUND",
  "FileType": "Sound",
  "FirmwareVersion": "1.50",
  "MetaInfo": {
    "Tags": [
      "LEAD"
    ]
  },
  "Samples": [
    {
      "FileName": "Samples/auto-test/square.wav",
      "FileSize": 96064,
      "Hash": "129070423"
    }
  ]
}

[dagargo]

As explained in #125, extracting the tags doesn't look trivial at all.

[dagargo]

In the end, the solution was to use the sound tags in the .metadata file.

This is an example.

{
  "metaversion": 2,
  "sample_references": [],
  "tagmask_src": {
    "offset": 8,
    "size": 4,
    "count": 1
  },
  "sound_tags": [
    "SNARE"
  ]
}

Added in f9d28f1.