[CMAKE] Add resource file to bitcoin-qt
[CMAKE] Add resource file to bitcoin-qt

Summary:
The resource file is missing from bitcoin-qt in the windows build. Other
executables have the resource file set correctly.

Test Plan:
  Cross build for Windows with CMake. Check the `bitcoin-qt.exe`
executable embeds its icon.

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D4256

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