Return full thumbail image in api

[dimasciput]

For #291

The new api will return :

{
    "total": 1,
    "next": null,
    "previous": null,
    "results": [
        {
            "resource_type": "Style",
            "uuid": "de3bd56f-1c49-43d7-97a8-ebc6008d6083",
            "name": "Cube",
            "creator": "creator",
            "upload_date": "2020-11-17T00:59:37.341000",
            "download_count": 1,
            "description": "This a cube",
            "file": "http://localhost:62202/media/styles/2023/qartoon.xml",
            "thumbnail": "http://localhost:62202/media/cache/be/7a/be7a1063302bd3a69734ee227bfa793b.jpg",
            "thumbnail_full": "http://localhost:62202/media/styles/2023/master_sword.jpg"
        }
    ]

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.01 🎉

Comparison is base (98041b0) 76.81% compared to head (16cfed7) 76.83%.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #295      +/-   ##
==========================================
+ Coverage   76.81%   76.83%   +0.01%     
==========================================
  Files         128      128              
  Lines        4810     4813       +3     
==========================================
+ Hits         3695     3698       +3     
  Misses       1115     1115              

Impacted Files	Coverage Δ
qgis-app/api/serializers.py	91.17% <100.00%> (+0.26%)	⬆️
qgis-app/api/tests/test_views.py	92.35% <100.00%> (+0.09%)	⬆️

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