fix modded key bindings never being registered on neoforge

[Nahida1212]

Problem

On NeoForge, Controlify never converts modded key mappings into controller
bindings, even though the Bindings API docs
state that "otherwise unhandled modded KeyMappings" are automatically
converted on both Fabric and NeoForge.

Symptoms on NeoForge (tested with Controlify 3.5.3+mc26.1 on MC 26.1.2):

• The controller bindings screen only shows Controlify's own  categories,
  never a category belonging to another mod.
• The radial menu editor's "Available Controls" list never shows generated
  bindings (the ones that use a book as their fallback icon).
• No Failed to automatically register modded keybind line is logged either,
  because ControlifyBindings#registerModdedBindings iterates over an empty
  collection.

Reported in / related to: #541, #572, #949