Monolithic Showcase PR adding features and reworking some parts of the plugin

[tGautot]

This PR serves as a showcase of all the features and reworks I have added to the plugin for people to test changes and give feedback to overall ease-of-use and architecture of the plugin. The different features should be slowly added to the main repo by smaller PRs in the future.

Here is a compact list of changes:

• Added image tracking.
• Fixed raycasting.
• Fixed uv-mapping of camera texture to handle all phone orientation (but limitiations (in the engine?) mean a shader in the project is still necessary, maybe someone can find an alternative)
• Separated plane tracking from plane rendering
• The branch also include changes to the demo, but these are mostly debug tools for myself, don't look too much into it.

What still needs to/can be done:

• While the image tracker creates and manages XRPositionalTracker, the plane tracker does not at this time.
• Rework the PlaneRenderer to work alonside the PlaneTracker and be togglable.
• Add other ArCore features (face tracking, cloud anchor, recording...)
• Update the README
• Clean up the demo

[thomascrow01]

have you tried your fork in Godot 4.5 or 4.6? I've been stuck for a while trying to get this to work on 4.6-stable and even tried 4.5.2-rc1 for a bit but have had no luck getting the camera background displaying anything

Also had an issue with the image and plane tracking crashing
I have been testing this on a Zebra TC58 (Android version 11)