(WiiU) Update WUT and add RetroArch target for WUHB files (Aroma enviroment)

Description

A few weeks ago, the WiiU received a new form of CFW called "Aroma", which runs apps under the WUHB extension.
What this is effectively creating a coldboot option for the system, and also adds a bunch of features and other things as plugins directly on boot.

One of said options is the ability to be able to run Homebrew apps straight from the WiiU's home menu, as if it they were official apps on the system. This way, each homebrew app can be threated as their own app within the system.

In order to make RetroArch compatible with this setup, an update of WUT is required, as well as having a TV logo image (tv_splash.png, 1280x720), the gamepad image (drc_splash.png, 854x480) and the home menu image (icon.png, 132x179).
With that, creating the WUHB file out of the rpx should be easy enough by following these recommended instructions after updating both wut and wut-tools:
https://gbatemp.net/threads/release-aroma-environment-for-wii-u.618474/page-17#post-9940681

Expected behavior

Updating to the Aroma-friendly WUHB format would allow for RetroArch to be recognized and properly loaded on the system, alongside their proper boot logo, icon, and message.

Actual behavior

RetroArch currently cannot run under this environment since; while Aroma does have support for RPX apps, upon loading it simply stays on a black screen.

Start by reviewing the WUT and wut-tools update requirements and the RPX-to-WUHB build path described in the issue. Check the required tv_splash.png, drc_splash.png, and icon.png assets, then verify that the generated WUHB loads under the Aroma environment with the expected logo, icon, and message.