Added logo upload feature

[ValdoTR]

/!\ WIP /!\

Adds the logo upload feature, which is basically another field type in the config panel that deals with the preview and the replacement of the old logo URL defined in a Tiled variable by a new one, uploaded by the user.

I called this 'logo' replacement but this could be really any image in Tiled.
You can test this with the map: 'configuration_logo.json'

TODO:

• Add a real upload API endpoint
• Work a little bit on the CSS
• Resize the actual file (not just its rendering)
• Refactore the whole code to use the Store instead of only the script part of Field.svlete

PS: This is working with a local upload (uploading locally the image in the disk and retrieving the path, then replacing the image)

[codecov-commenter]

Codecov Report

Merging #81 (32cfec4) into main (5bb55b0) will not change coverage.
The diff coverage is n/a.

❗ Current head 32cfec4 differs from pull request most recent head 3f6c8e3. Consider uploading reports for the commit 3f6c8e3 to get more accurate results

@@           Coverage Diff           @@
##             main      #81   +/-   ##
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  Coverage   55.17%   55.17%           
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  Files           1        1           
  Lines          29       29           
  Branches        5        5           
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  Hits           16       16           
  Misses         13       13           

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