Add application emojis

[Rapougnac]

Description

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Connected issues & other potential problems

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Type of change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• Ran dart analyze or make analyze and fixed all issues
• Ran dart format --set-exit-if-changed -l 160 ./lib or make format and fixed all issues
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

[kingmigdor]

I am getting the following error while testing:

Error: type '_Map<String, dynamic>' is not a subtype of type 'List<dynamic>' in type cast
Stack trace: #0      ApplicationManager.listApplicationEmojis (package:nyxx/src/http/managers/application_manager.dart:220:25)

This is due to the returned body not actually being a List. It's Map<String, dynamic> with the "items" key being a List. I tried printing out an empty result on this:

{items: []}

Not sure what's the direct cause of this is though.