wcst_import - old recipes (e.g: map mosaic) does not read colorPaletteTable properly

[Bang Pham Huu]

This should read the content of file from colorPaletteTable properly in old recipes as same as in general recipe, instead of reading as string literal metadata, e.g:

<colorPaletteTable>color_palette_table_rasql_READY.cpt</colorPaletteTable>

{
  "config": {
    "service_url": "http://localhost:8080/rasdaman/ows",
    "tmp_directory": "/tmp/",
    "mock": false,
    "track_files": false,
    "automated": true
  },
  "input": {
    "coverage_id": "Germany_2D_B04_10m",
    "paths": [
      "Germany_2D_B04_10m.tiff"
    ]
  },
  "recipe": {
    "name": "map_mosaic",
    "options": {
        "coverage": {
            "metadata": {
                "type": "xml",
                "global": "auto",
                 "colorPaletteTable": "color_palette_table_rasql_READY.cpt"
             }
        },
        "scale_levels": [4, 8, 16],
        "wms_import": true
    }
  }
}