Better support for custom blocks

[manuq]

What Happened

Currently all block definitions are read by traversing addons/block_code/blocks/ in search for .tres resource files. Then there is also a way to dynamically add custom blocks by defining func setup_custom_blocks() in a script (example).

It would be nice to unify and only have resource files. For that, it seems that we need to define a resource loader and change the extension from .tres to something like .blockdef. Then we can get rid of the custom traversing and port the dynamic definitions to their own files.

How to Reproduce

N/A

Block Coding Plugin Version

No response

Godot Engine Version

No response

Operating System

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Logs or command-line output

No response

Anything else?

No response