Update extension support table

[aaronfranke]

This PR updates the extension support table.

• Collapse the 3 header rows into 2. The distinction between types of tools is not useful or helpful, and is in fact inaccurate, as you can use game engines both as a consumer of content or a tool to author content.
• Add links for most ✅ and 🚧 emojis.
• Add 🏆 and 🧩 emojis to indicate if it's available out of the box built into the engine (🏆) or as a plugin (🧩).
• For KHR_audio_emitter:
  • Anything that hasn't been updated since it was called OMI_audio_emitter was set to ❌
  • Anything that hasn't been updated since it was called KHR_audio was set to 🚧
  • Add 🚧🏆 for Godot and links to PRs (marked as WIP because it's not merged yet)
• For 3OV:
  • Shorten its name from Three Object Viewer to just 3OV.
  • Fix missing fields for 3OV, the column was missing rows.
  • Add ✅🏆 for OMI_spawn_point.
• For Godot:
  • Add ✅🏆 and ✅🧩 emojis for many extensions.
  • Collapse runtime/editor into one, since the distinction is not useful at least not now, it's trivially easy for an extension to support both runtime and the editor, the same code supports both at once.
• Remove Mozilla Hubs because it is shutting down in less than 2 months from now.

Before:

After:

[antpb]

Nice changes. Reads clear to me 👍